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PART 3
EXCLUSIONARY RULES AND
EXCEPTIONS
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CHAPTER 6
Evidence of Opinion
“Opinion” may be defined as an inference drawn from perceived facts.! The
general rule is that evidence of opinion is not admissible. However, the rule is
subject to certain well-known exceptions, particularly relating to expert evidence.
1. GENERAL RULE
The general rule is that while evidence of fact is admissible, evidence of opinion
is not. This rule flows from the principle that while witnesses give evidence as to
facts, the inferences to be drawn from those facts are matters for the jury. Thus, in
a murder case, a witness may say “A shot B”. He may not say “A killed B”
because it is for the jury to determine whether A killed B, i.e. whether the shot
caused B’s death.
The rule may be further illustrated as follows. Suppose a smash and grab raid
has taken place at a jeweller’s shop. A witness in a nearby street heard the crash
of the breaking glass. Shortly afterwards he saw a man running into the street
from the direction of the jeweller’s shop. The man was carrying jewellery and his
hands were bleeding. The obvious inference is that the man was the thief. In
ordinary speech the witness would say “I saw the thief’. However, when giving
evidence the witness may only say what he saw. He may not say that the man was
the thief. That is an inference for the jury to draw.
There are essentially two reasons for the rule excluding evidence of opinion.
They are as follows:
1. The opinion of the witness is irrelevant. Thus, in the example given above,
the opinion of the witness that the man he saw was the thief does not matter. The
relevant parts of his evidence are those involving what he saw and heard. A
familiar example of the same principle is the eye-witness in a case of dangerous
driving. He may give evidence of what he saw. He may not, however, give his
opinion as to whether the defendant’s driving was dangerous.
Similarly, the opinion of the non-expert witness as to a matter requiring expert
evidence is irrelevant and inadmissible. Thus, if a person is attempting to
establish a defence of insanity, he may not call his friends and relations to give
evidence of their opinion on the subject. In Loak? a friend of the defendant and a
magistrate were not allowed to give evidence of their opinion that the defendant
was insane.
' Landau (1944) 60 L.QR. 201.
2 Loak (1911) 7 Cr.App.R. 71.
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2. If evidence of opinion is admitted, the function of the jury, i.e. to decide on
the “ultimate issue”, will be usurped. This is the primary reason for the rule. It is
thought that it is the reason why the rule was developed.*
A witness cannot, therefore, say that in his opinion the defendant is guilty.
Thus, a bystander cannot say that A was driving dangerously, a store detective
cannot say that B stole the goods from the shops; an eye-witness cannot say C
murdered D. These are all issues which the jury have to decide. For example,
evidence is not admissible as to (a) whether an article is such as to “tend to
deprave and corrupt” under s.1 of the Obscene Publications Act 1959*; or (b)
whether a driver is unfit to drive through drink or drugs®; or (c) whether a
defendant intended to commit a particular crime or not.° In Chard’ a prison
doctor was not permitted to say that in his opinion the defendant who was
charged with murder had not intended at the time of the offence to commit
murder. The Court of Appeal held that this evidence had been rightly excluded
because it went to the very issue which the jury had to decide. The Court said:
“It is not permissible to call a witness, whatever his personal experience, merely to
tell the jury how he thinks an accused man’s mind—assumedly a normal
mind—operated at the time of the alleged crime with reference to the crucial
question of what the man’s intention was.”*
An example is to be found in Jeffries.° The defendant in that case was charged
with possessing drugs with intent to supply them. At trial a detective constable
gave evidence that in her opinion certain lists found at the defendant’s flat related
to the sale of drugs. The Court of Appeal held that this evidence should not have
been admitted because the officer was essentially giving her opinion on the
ultimate issue, namely whether the defendant had the drugs in his possession with
intent to supply them (although she was entitled to give evidence, based on her
experience, as to value and prices).
It follows that questions must be framed in such a way as to avoid the risk that
the witness will give an opinion on the ultimate issue which the jury have to
decide. Thus, if a victim has died of gunshot wounds, an eyewitness should be
asked “Did A shoot at B?”; “Did the shot hit B?”; and not “Did A kill B?”
However, the rule that witnesses may not be asked questions as to the
“ultimate issue” is subject to modification in the case of expert witnesses. Thus,
questions on the ultimate issue are allowed if it would be artificial for the witness
not to express his opinion on that issue. In the case of insanity, for instance, a
medical witness may be asked in cross-examination whether in his opinion the
conduct of the defendant immediately after a murder would indicate that he knew
(a) the nature and quality of the act; (b) that the act was contrary to law.'°
The reasons for allowing such questions may be summarised:
3 Landau (1944) 60 L.Q.R. 201.
4 Calder & Boyars Ltd [1969] 1 Q.B. 151; Anderson [1972] 1 Q.B. 304.
5 Davies (1962) 46 Cr.App.R. 292.
6 Chard (1972) 56 Cr.App.R. 268.
7 Chard (1972) 56 Cr.App.R. 268.
8 Chard (1972) 56 Cr.App.R. 268 at 270-271.
9 Jeffries (1997) Crim.L.R. 819.
1 Holmes (1953) 37 Cr.App.R. 61.
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(i) Since the expert’s opinion may have been obvious from his evidence, it
would be artificial not to allow him to express it merely because it is on an
ultimate issue.
(ii) The defence may be hampered in presenting their case if the expert may not
be asked about that issue in the most direct way.
In fact, the tendency to allow experts to give evidence on the ultimate issue
had been recognised by the courts as long as 50 years ago.'! The practice was
sanctioned by the Court of Appeal in Stockwell.!? In that case the defendant was
charged with robbery. The only issue was identification. The prosecution were
permitted to call a “facial mapping” expert who gave his opinion that the
defendant was the robber as shown on photographs taken by security cameras.
The Court of Appeal held that this evidence was admissible although it was on
the very issue which the jury had to decide. Lord Taylor CJ said that the old rule
was more a matter of form than substance and had been more honoured in the
breach than the observance. The Lord Chief Justice said that an expert should be
allowed to give his opinion on an ultimate issue subject to a direction by the
judge to the jury that they are not bound by it.
A witness may, similarly, state an opinion on an ultimate issue if it is a way of
conveying relevant facts perceived by him. The statement is then admissible as
evidence of what the witness perceived. Thus, a witness in a case of wounding
may say that he saw several people attack the defendant who then took up a
weapon “to defend himself”. He will not be stopped if he says this, although the
question whether the defendant was defending himself or not is one for the jury to
decide. To say that the defendant took up the knife in self-defence is merely to
describe the way in which a weapon was taken up under pressure of attack.
2. EXCEPTIONS TO THE GENERAL RULE
A. The opinions of non-experts
Evidence of the opinion of non-experts is not generally admissible. However,
such evidence is admitted on certain topics. The most common example is a
witness’s opinion as to a person’s identity (considered in Ch.14). Four other
exceptions are considered below.
(1) Matters of impression and narrative
Evidence of the opinion of a witness who is not an expert may be admissible if
(a) the impression received by the witness is too vague to be otherwise described;
or (b) if made as a way of conveying relevant facts perceived by him.
DPP v A. & B.C. Chewing Gum [1968] A.C. 159 at 164, per Lord Parker CI.
2 Stockwell (1993) 97 CrApp.R. 20. See also Atkins (Dean) and Atkins (Michael) [2010] 1
Cr.App.R. 117(8) in relation to expert evidence on facial mapping.
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A witness may say that the person he saw was a “young woman” or a “child of
about five”.'> He may state the impression as to the speed of the car!'+ or
(provided he states the facts upon which he relies) whether a person has taken a
drink or not.'> Therefore, if an eye-witness of an accident says “there was nothing
the driver could do to avoid the accident”, he has described accurately the
impression which the event made on him.
(2) Witness’s own condition
6-09 A witness may give evidence of his own condition, whether physical or mental.
Such evidence may include evidence of opinion. Thus a witness may say “I had
seven pints of beer to drink, but I was not drunk” or “I was well until I ate the
food given me by the defendant, then I fell ill”.
A witness may likewise give evidence (a) as to his motive for doing a
particular act; or (b) as to what his feelings were. For example, in a case of
robbery the witness may say that he handed over the goods to the defendant
because he was frightened that if he did not, he would be injured or a witness may
state that in his opinion a threat that he would “suffer as before” was a threat to
burn his house down.'¢
(3) Handwriting
6-10 Whether a particular sample of handwriting is that of a particular person is one
matter where the evidence of a non-expert witness may be admitted. In practice,
such evidence is rarely tendered. However, the Criminal Procedure Act 1865 s.8,
provides that comparison of a disputed writing with any writing proved to be
genuine shall be permitted and the evidence of witnesses on the subject is
admissible as evidence of the genuineness or otherwise of the disputed writing. In
some instances, evidence by a lay witness may be preferred to that of an expert.!”
The witness must be acquainted with the defendant’s writing and is open to
cross-examination as to the extent of his acquaintance. He may have seen the
particular person write; he may have received letters from him; or he may have
seen, in the ordinary course of business, documents purporting to be in the
particular person’s handwriting. But he must not have become acquainted with
the person’s handwriting simply for the purposes of the trial.'®
A jury must not be asked to compare two pieces of handwriting; in such
circumstances they must have the opinion of an expert witness to guide them.'° In
some cases, however, in which no expert has been called, jurors have before them
'S Cox [1898] 1 Q.B. 179; Wallworth v Balmer [1966] 1 W.L.R. 166. The court may determine a
person’s age: Children and Young Persons Act 1933 s.99; Criminal Justice Act 1948. s.80(3);
Magistrates’ Courts Act 1980 s.150(4).
'4 But the Road Traffic Regulation Act 1984 s.89(2) provides that a person shall not be liable to be
convicted solely on the evidence of one witness that in his opinion the person prosecuted was driving
the vehicle at a speed exceeding the specified limit.
'S Davies (1962) 46 CrApp.R. 292; Neal [1962] Crim.L.R. 698; Tagg[2002] 1 Cr.App.R. 22.
16 (1850) 4 Cox 243.
17 Fuller v Strum, The Times, 14 February 2001, ChD.
18 Crouch (1850) 4 Cox 163; Rickard (1918) 13 Cr.App.R. 140. The opinion may be based on
comparison from a photocopy: Lockheed Arabia v Owen [1993] Q.B. 806.
19 Tilley (1961) 45 Cr.App.R. 360; Smith (1968) 52 Cr.App.R. 848.
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specimens of handwriting, one of which is disputed. The Court of Appeal in
O’Sullivan®® recognised that, in such circumstances, it is unavoidable that the
jury may try to make comparisons; but there must never be an invitation or
exhortation to a jury to look at disputed handwriting (and try to make
comparisons). “There should be a warning of the dangers; further than that, as a
matter of practical reality, it cannot be expected that the court will go.”?!
(4) Voice recognition
In Flynn and St John? the Court of Appeal held that the admissibility of lay
listener voice recognition evidence depends on the degree of familiarity of the
witness with the suspect’s voice. It was recognised that the danger of
misidentification always exists, even more so where the voice recording is poor.
It follows that the increasing use of lay listener evidence from police officers
must be greeted with both caution and care. Thus, where the prosecution seeks to
rely on such evidence it is preferable to instruct an expert to give an independent
opinion. Whether expert or lay listener evidence is admitted, the judge must
always give a careful direction warning the jury of the danger of possible
mistakes in such cases.??
B. The opinions of experts
The chief exception to the general rule that evidence of opinion is not admissible
relates to the evidence of experts. An expert is a person who is required to give or
prepare expert evidence for the purpose of criminal proceedings. The purpose of
expert evidence is to provide the court with information which is outside the
experience of a judge or jury.?+
The remainder of this chapter is concerned with a discussion of this exception.
(1) Admissibility
The opinion of experts is admissible on those matters which require such
evidence, that is, where the subject is one which competency to form an opinion
can only be acquired by a course of special study or experience. “In matters of
science, no other witnesses can be called.”?> Such evidence is preserved by
s.118(1) of the Criminal Justice Act 2003, which preserves certain common law
categories of admissible hearsay, including “any rule of law under which in
criminal proceedings an expert may draw on the body of expertise relevant to his
field”.
It is for the court to decide whether or not a particular point requires expert
evidence; if the court decides that it does not, then the point in question must be
proved either without the admission of opinion evidence at all or by non-expert
2 O'Sullivan [1969] 2 All E.R. 237.
21 O'Sullivan [1969] 2 All E.R. 237 at 242, per Winn LJ.
2 Flynn and St John [2008] 2 Cr.App.R. 266(20).
23 For consideration of when and in what cases voice identification expert evidence may be of
assistance, see Hersey [1998] Crim.L.R. 281. See also para.14~52 for voice identification.
24 Turner [1975] 1 Q.B. 834.
25 Folkes v Chadd (1782) 3 Doug. K.B. 157, per Lord Mansfield.
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evidence. “In each case it must be for the judge to decide whether the issue is one
on which the jury could be assisted by expert evidence.”?°
Account must be taken of advances in scientific expertise. In Clarke?’ the
Court of Appeal said that there were no closed categories where expert evidence
may be placed before the jury. It would be wrong to deny the law of evidence the
advantages to be gained from new techniques and advances in science.
Accordingly, the tendency is to admit expert evidence on a point unless it is
apparent that it is not a matter for expertise. Certain types of expert evidence are
not yet of sufficient scientific status to be acceptable, see para.6—18, below.
However, once a scientific test is recognised as being reliable, an appropriate
expert can give evidence as to its result.”*
In Cannings”? it was held that juries should not be placed in a position where
they must choose between the opinion of expert witnesses where there was no
cogent evidence supporting either expert’s stance. The Court of Appeal held that
the prosecution of a parent for murder should not be commenced if the outcome
of the trial depended exclusively on a serious disagreement between distin-
guished and reputable experts as to the cause of death, unless there was
evidence—additional to the expert evidence—supporting the conclusion that the
infant was deliberately harmed.
In Clare and Peach*® a police officer who had made a study of video
recordings depicting scenes of violence after a football match was allowed to
give evidence in order to identify offenders shown on the recordings. The Court
of Appeal referred to a New Zealand case in which such a witness was described
as “sufficiently expert ad hoc to give identification evidence”.*! The Court of
Appeal did not comment on whether the expression “expert ad hoc” was suitable
in these circumstances. It is submitted that it is not, since such a witness cannot
be described as an expert.*?
6-14 If, however, the matter is one upon which an expert should give evidence, the
court should refrain from acting as its own expert. Thus, the Divisional Court
held that justices acted wrongly when, in a case concerning defective tyres, they
called for a tyre gauge and then retired with the tyres and the gauge without any
evidence being given as to how the gauge should be operated.** Similarly, the
Court of Appeal has criticised a judge for appearing to turn himself into a
handwriting expert by comparing examples of the defendant’s handwriting.*4 In
Akhtar v Grout,*®> a prosecution under the Trade Marks Act 1994, it was held that
expert evidence was admissible to supplement the knowledge and experience of
26 Stockwell (1993) 97 Cr.App.R. 260 at 264, per Lord Taylor CJ.
27 Clarke [1995] 2 Cr.App.R. 425. The expertise in this case was facial mapping by video
superimposition. This is now an accepted form of expert evidence: Atkins (D&M) [2009] Crim.L.R.
141. See also Donald [2004] Crim.L.R. 841 where facial mapping was admitted when there had been
a failure to hold an identification parade.
28 7 [2012] CrimL.R. 886.
2° Cannings (2004) 2 Cr.App.R. 63(7).
%© Clare and Peach [1995] 2 Cr.App.R. 333, cited at para.2-39, above.
31 Howe [1982] 1 N.Z.L.R. 618.
%° For further discussion of this topic, see Elliott, “Video Tape Evidence: The Risk of Over
Persuasion” [1998] Crim.L.R. 159.
33 Tiverton Justices Ex p. Smith [1980] R.T.R. 280.
4 Simbodyal, The Times, 10 October 1991.
38 Akhtar v Grout (1998) 162 J.P. 714.
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justices as to whether or not certain clothing was not genuinely what the trade
marks indicated that it should be. As a matter of law, the mere fact that, if justices
accept the evidence of the expert it would be conclusive of the question put to the
court, is not by itself a reason for excluding the evidence. In O Toole v Knowsley
MBC* the Divisional Court held that justices should not have refused to accept
the uncontradicted advice of experts (in a case of statutory nuisance under the
Environmental Protection Act 1990). The issue was preeminently a matter of
expert evidence which the justices should have taken into account and they had
been wrong in refusing to do so.
If expert evidence is to be rejected there must be some logical basis for doing
so: Gregory v DPP?’ in which it was held that the evidence of a toxicologist
which raised significant doubts as to the accuracy of blood alcohol tests should
not have been rejected.
On the other hand, if information is within the knowledge of the court or the
issue is one which the court can decide of its own experience, expert evidence
will not be admitted.
“If on the proven facts a judge or jury can form their own conclusion without help,
then the opinion of the expert is unnecessary. In such a case if it is dressed up in
scientific jargon it may make judgment more difficult. The fact that an expert
witness has impressive scientific qualifications does not by that fact alone make his
opinion in matters of human nature or behaviour within the limits of normality any
more helpful than that of the jurors themselves; but there is a danger that they may
think it does.”**
Thus, in Chard*° the evidence of a prison doctor was not admitted when the
purpose was to show that the defendant did not have the necessary mens reato
commit murder and in Turner*° the evidence of a psychiatrist was not admitted
when the purpose was to show that a man charged with murder was likely to have
been provoked.
The same applies where the issue in question is not a scientific matter. Thus, in
Wahab*' it was held to be inappropriate to call expert evidence of one solicitor
criticising the competence of another since the judge did not need the expert legal
evidence to form a view about the reliability of the confession.
There are difficulties sometimes in disentangling questions of opinion from
questions of fact.4? This distinction is particularly important when considering the
evidence of experts. This is because the function of the expert witness is twofold.
First, he may give his opinion upon an issue in the case (i.e. inferences which
he draws from perceived facts as a result of his knowledge and experience).
Secondly, he may give evidence of facts which his training has equipped him to
6 O'Toole v Knowsley MBC, The Times, 21 May 1999.
37 Gregory v DPP [2002] 166 J.P. 400 (QBD).
38 Turner [1975] 2 Q.B. 834, per Lawton LJ.
© Chard (1972) 56 Cr.App.R. 268, 270. See also Wood (1989) 153 J.P. 20 where the Divisional Court
held that magistrates were right to reject certain evidence given by a consultant psychiatrist on the
ground, inter alia, that it dealt with matters within the knowledge and experience of the court.
4 Turner [1975] 2 Q.B. 834. Note that the common law defence of provocation has now been
replaced by the statutory partial defence of loss of control: Coroners and Justice Act 2009 ss.54—56.
41 Wahab [2003] 1 Cr.App.R. 232.
® Landau (1944) 60 L.Q.R. 201.
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perceive, but which would not be observed by a layman, i.e. “something
perceptible upon physical examination but which would be recognised only by
someone possessed of special knowledge or experience”.*>
These functions are often combined. Thus, the fingerprint expert points out the
“ridge” characteristics of a certain print. These are matters of fact. He compares
the print with the defendant’s fingerprint and draws the inference that the
defendant made the print in question. That is a matter of opinion. This distinction
between evidence of fact and evidence of opinion may be of importance when
assessing the expert’s evidence.
6-17 The expert may, like any other witness, give evidence of fact. He may give
evidence of fact which is not within his field of expertise. In this case, the jury
must be directed that the witness was not speaking as an expert. Thus, in Cook
the defence to a charge of murder was provocation. A pathologist gave evidence
that, as a matter of personal (but not medical) opinion, the blows to the victim
were not consistent with having been inflicted by someone in a frenzy. There was
held to have been a material irregularity in the case in that the judge in summing
up had indicated that the pathologist had spoken as an expert and the jury might
have attached far greater weight to his view than it merited.*°
An expert’s inadmissible opinion (outside his area of expertise) does not
become admissible when adduced on behalf of a co-defendant. In Theodosi*® T
and a co-defendant were both charged with causing death by dangerous driving.
Each blamed the other for the offence. A police officer gave evidence of the
estimated speed of T’s car. In cross-examination counsel for the co-defendant
adduced the police officer’s opinion that T was wholly to blame for the accident.
The Court of Appeal held that the trial judge should have discharged the jury
because inadmissible and very prejudicial evidence had been given.
6-18 The subjects of expert evidence fall into a number of broad categories; the
most common are matters of science, art or skill, for example the evidence of
medical practitioners as to the cause of injury or death; mechanical experts as to
the functioning of a motor car; handwriting or fingerprint experts on the subject
of their expertise. The categories of expert evidence will expand as new
techniques are developed and new advances in science are made.‘ So long as the
field of expertise is sufficiently well-established to pass ordinary tests of
relevance and reliability no enhanced tests need be applied: Dallagher.**
Examples include lip-reading evidence;*° historical evidence from an expert
engaged in the study of terrorism;*° and linguistic evidence as to the meaning of
code words.*!
3 Law Reform Committee, 17th Report, Evidence of Opinion and Expert Evidence, Cmnd. 4489,
para.7.
Cook [1982] Crim.L.R. 670.
45 Since the pathologist was speaking outside his field of expertise, it must be doubtful whether his
view should have any weight.
46 Theodosi, The Times, 13 April 1992.
47 See Clarke [1995] 2 Cr.App.R. 425, above, at para.6-13.
“8 Dallagher [2003] 1 Cr.App.R. 195.
49 Luttrell, Dawson and Hamburger (2004] Crim.L.R. 939.
5° Ahmed (Rangzieb) and Ahmed (Habib)(2011] Crim.L.R. 734.
51 Nguyen [2007] NSWCCA 249.
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Not all topics on which expert opinions are available are admissible as
evidence. For instance, in Gilfoyle,** it was held that the evidence of a
psychologist relating to a “psychological autopsy” was not expert evidence of a
kind properly to be put before the court since, inter alia, the academic status of
such autopsies was not such as to permit them to be admitted as a basis for expert
opinion. It has also been held that post-hypnosis evidence is unreliable and
therefore inadmissible.°* And in Dallagher** evidence of ear prints was not
admitted; although there was no objection in principle, the expertise was in its
infancy and conclusions could not be expressed in terms of statistical probability.
It is for the court to decide whether a point requires expert evidence. In
Kempster*> it was acknowledged that car print comparison was capable of
providing information that could identify a person who had left an ear print on a
surface, but it would only be safe to rely upon such evidence where the minutiae
of the ear structure could be identified and matched.
Subjects will now be considered where there are particular considerations in
relation to expert evidence, namely psychiatric evidence, sudden unexplained
infant death and “shaken baby cases”, cases of obscenity, special measures
directions, and credibility of witnesses.
Psychiatric evidence. In some cases psychiatric evidence is a necessity.°°
Thus, it is a practical necessity in order to establish a defence of automatism*’ or
diminished responsibility.** Despite authority to the contrary*® it is also difficult
to see how a defence of insanity could succeed in the absence of medical
evidence. Where the possible effect of hypoglycaemia on intent has to be
considered, expert evidence is required since the matter is outside the experience
of ordinary jurors.°°
Reliability of a confession. Expert evidence may also be admissible to assist
the judge and jury in assessing the reliability of a confession. In O’Brien, Hall
and Sherwood,°! the Court of Appeal said that, where expert evidence of the
abnormality of a defendant’s personality is to be admitted as being relevant to the
reliability of a confession, there must be a significant deviation from the norm
and also a history predating the confession (not based solely on the history given
5 Gilfoyle [2001] 2 Cr.App.R. 57. See also Stagg unreported, 14 September 1994 CCC, per Ognall J,
Archbold News, issue 9, 4 November 1994, where it was doubted whether psychological profiling
could properly be described as expert evidence.
53 Trochym v The Queen 216 CCC (30) 225, Supreme Court of Canada.
S* Dallagher [2003] 1 CrApp.R. 195.
55 Kempster [2008] 2 CrApp.R. 19.
56 For a discussion of psychiatric evidence, see Kenny, “The Expert in Court” (1983) 99 L.Q.R. 197;
and for a discussion of the role of the expert, see Gee, “The Expert Witness in the Criminal Trial”
[1987] Crim.L.R. 307. Not all categories of psychiatric evidence are admissible: see Gilfoyle and
Stagg, above.
57 Hill v Baxter [1958] 1 Q.B. 277 at 285, per Devlin J; Smith (1979) 69 Cr.App.R. 378 at 385, per
Geoffrey Lane LJ; Bratty v Att-Gen [1963] A.C. 386 at 413, per Lord Denning.
5 Byrne [1960] 2 Q.B. 396; Dix (1982) 74 Cr.App.R. 306. “While the subsection does not in terms
require that medical evidence be adduced in support of a defence of diminished responsibility, it
makes it a practical necessity if that defence is to begin to run at all”: Dix, above, at 311, per Shaw LJ.
5 4u-Gen for S. Australia v Brown [1960] A.C. 432; (1960) 44 CrApp.R. 100 at 112, 113.
© Toner (1991) 93 Cr.App.R. 382.
6! O'Brien, Hall and Sherwood, The Times, 16 February 2000.
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by the subject) which pointed to or explained the abnormality. The jury should be
directed that they were not obliged to accept the evidence but should consider it,
if they think right, as throwing light on the personality of the defendant and
bringing to their attention aspects of his personality of which they might
otherwise be unaware. In Blackburn the Court of Appeal said that O’Brien, Hall
and Sherwood was not a comprehensive statement as to the circumstances when
expert evidence will be admissible on the reliability of a confession. Blackburn
concerned the phenomenon of “coerced compliant confession” arising often from
fatigue when an individual (in this case a boy of 15 who was questioned for over
three hours) experiences a strong desire to give up refusing suggestions put to
him. In Raghip® the defendant was aged 19 but was of low IQ and had the
reading age and level of functioning of a child under 10 years old. In these
circumstances the Court of Appeal said that psychological evidence was
necessary and admissible to assist the jury in assessing the reliability of a
confession made by R. The Court drew a distinction between evidence admissible
for this purpose and such evidence relating to a defendant’s mens rea (which is
generally inadmissible). In Ward the Court of Appeal held that expert evidence
of a psychiatrist or psychologist may be admitted if it is to the effect that the
defendant is suffering from a condition not properly described as mental illness,
but from a personality disorder so severe as to be categorised as a mental
disorder.
In Pora v The Queen® the Privy Council held that evidence from a clinical
psychologist that the appellant’s confessions to rape and murder were unreliable
because he suffered from foetal alcohol spectrum syndrome was inadmissible.
The court said that it was the duty of an expert to provide material on which a
court could form its own conclusions on relevant issues, and that an expert
witness should be careful to recognise the need to avoid supplanting the court’s
role as the ultimate decision maker on matters that were central to the outcome of
the case.
6-21 In Lowery v The Queen, the Privy Council upheld the evidence of a
psychologist, called by one of two co-defendants charged with murder, to the
effect that the defendant was less likely on the grounds of personality to have
committed the murder.°”
On the other hand, psychiatric evidence will not be admitted if the issue is one
which the jury should determine without assistance. The question is whether the
jury require the help of a psychiatrist in deciding the issue or not. Will the
psychiatrist tell the jury something which they do not know from their own
knowledge and experience?
® Blackburn [2003] 2 Cr.App.R. 440(3).
® Raghip, The Times, 9 December 1991.
64 Ward (1993) 96 Cr.App.R. 1 at 66.
65 The Times, April 20, 2015.
86 Lowery v The Queen [1974] A.C. 85.
87 Lowery has been distinguished as a decision on its own special facts because the evidence was
called on behalf of one defendant to rebut the evidence of his co-defendant: Turner [1975] Q.B. 834 at
842: Masih [1999] Crim.L.R. 395. Accordingly it would appear that Lowery cannot be taken as
establishing any general rule relating to the admissibility of psychiatric evidence.
112
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In all the following examples the essential point is that the issue of the
defendant’s state of mind is one that the members of the jury can judge for
themselves.
The leading case is Turner®® in which the defendant was charged with
murdering his girlfriend who admitted to sleeping with other men and to being
pregnant by another man. The defendant’s defence was provocation and he
sought to admit psychiatric evidence to the effect that he had had a deep
emotional relationship with his girlfriend and that her admissions were likely to
have caused a blind explosion of rage. He was not, however, suffering from a
mental illness. The Court of Appeal held that the trial judge had been right to
exclude the psychiatric evidence. A similar approach will most likely be taken to
the partial defence of “loss of self-control” which has now replaced the abolished
defence of provocation.
The Court said that (i) the question whether the defendant suffered from
mental illness was within the expert’s province, but was not relevant since it was
not in issue; (ii) the remaining points in the psychiatrist’s opinion were matters
which were well within ordinary human experience. The Court commented that
“Jurors do not need psychiatrists to tell them how ordinary folk who are not
suffering from a mental illness are likely to react to the stresses and strains of
life”.”°
If there is an underlying medical condition which the defendant claims made
him unable to commit the crime alleged there must be an organic or psychiatric
connection between the condition and the inability to commit the crime. In
Loughran” where the defendant was charged with rape and robbery he sought to
adduce psychiatric evidence that, due to an underlying physical condition, he
suffered from pathological anxiety at the prospect of sexual intercourse which
tended to confirm his contention that he was incapable of sexual intercourse. The
Court of Appeal held that the evidence had been rightly excluded since it went to
the defendant’s credibility and did not furnish information outside the jury’s own.
experience.
In Masih” the defendant, who was charged with rape, sought unsuccessfully
to adduce psychiatric evidence to the effect that his low intelligence and
immaturity made him easily led by his two co-defendants. However, although his
intelligence was low, it was within the scale of normality. The Court of Appeal,
upholding the trial judge, said that in these circumstances expert evidence was
not as a rule necessary and should be excluded, but that if a person came into the
class of mentally defective (i.e. with an IQ of 69 and below) and mental
defectiveness was relevant to an issue, expert evidence should be admitted; the
evidence should be confined to an assessment of the defendant’s IQ and an
explanation of any relevant abnormal characteristics which such an assessment
involved. In Jackson-Mason”* the Court of Appeal held that the principle in
Turner [1975] Q.B. 834.
® Coroners and Justice Act 2009 s.56(1).
7 Turner [1975] Q.B. 834 at 841.
7 Loughran [1999] Crim.L.R. 404.
7 Masih [1999] Crim.L.R. 395. See applied in Henry [2006] 1 Cr.App.R. 118(6) which concerned a
defendant with an IQ of 71.
73 Jackson-Mason [2015] 1 Cr.App.R. 6.
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Antar* (that evidence from a psychologist that the defendant had a very low IQ,
and that his suggestibility level was higher than that of the general population)
did not extend to cases that did not involve the defence or duress or in
circumstances where suggestibility might otherwise be in issue, such as
confession evidence.
In Reynolds,” a defendant charged with murder wished to call a psychiatrist to
give evidence that his ability to separate reality from fantasy was flawed. The
trial judge refused to admit the evidence. The Court of Appeal held that this
ruling was correct: the evidence was irrelevant. This was because the issue in the
case was whether the defendant had the necessary intention or not and there was
no suggestion in the evidence that he had been fantasising at the time of the
killing. The Court said that even if there had been such a suggestion, it amounted
to a personal trait, about which the jury could use their common sense and did not
require psychiatric evidence.
Some Commonwealth courts have taken a less restrictive view.”° In Lupien”’ a
majority of the Supreme Court of Canada held that psychiatric evidence should
have been admitted to show that a defendant would react violently to homosexual
advances.’* In Schultz’? the Supreme Court of Western Australia held that
psychiatric evidence was admissible on the issue of intent in a case of murder to
establish that the appellant was of borderline mentally defective intelligence with
an IQ of between 69 and 78. Burt CJ said that the evidence, if accepted, would
“take the appellant outside the range of the ordinary and would alert the jury to
the fact... that he was in a class apart”.*° However, the Court of Appeal said in
Masihthat Schultz went too far and would not be followed.
Thus, as a general rule, it would appear that the court should distinguish
between a case where the defendant suffers from mental illness or abnormality of
mind (in which case psychiatric evidence is admissible to assist the jury) and a
case in which there is no mental illness or abnormality of mind (in which case the
jury can draw on its own knowledge and experience without assistance). It is
sometimes argued that this test cannot be applied because mental abnormality and
illness cannot be precisely defined.’' However, the question whether mental
illness or abnormality exists in a particular case is for the court to determine on
the evidence before it. Each case must be decided on its own facts.*?
74 Antar, The Times, 4 November 2004.
75 Reynolds [1989] Crim.L.R. 220.
7 See Pattenden, “Conflicting Approaches to Psychiatric Evidence” [1986] Crim.L.R. 92 for a
comparison of the approaches in England, Canada and Australia.
77 Lupien 1970 S.C.R. 263. For a discussion of decisions on this topic and a plea that Turner, above,
should be reconsidered, see Mackay and Colman, “Equivocal Rulings on Expert Psychological and
Psychiatric Evidence” [1996] Crim.L.R. 88.
78 “Lupien 1970 S.C.R. 263, per Ritchie, Spence and Hall JJ. The author is grateful to Judge Gordon
Killeen, Senior Judge for the County of Middlesex, District Court of Ontario, for pointing out this
result.
7 Schultz [1982] W.A.R. 171.
8 Schultz [1982] W.A.R. 171 at 174,
81 See, e.g. Pattenden, “Conflicting Approaches to Psychiatrie Evidence” [1986] Crim.L.R. 99-100
and Mackay and Colman, “Excluding Expert Evidence” [1991] Crim.L.R. 800, where the authors
suggest that the present rule is too restrictive and that expert evidence should be admitted if the
defendant exhibits any abnormality of mind or personality.
82 Weightman (1991) 92 Cr.App.R. 291 at 297, CA.
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Sudden unexpected deaths in infancy. Cases involving the sudden
unexpected death of an infant and the death of a child from sudden brain bleeding
and swelling with no evidence of external injury (shaken baby syndrome) have
posed particular difficulties for courts in establishing the cause of death.
Disagreement between experts and conflicting data and research present the
courts with a real problem: if the experts cannot agree about such conflicting data
and research, how can a jury be expected to reach a conclusion beyond
reasonable doubt in cases that turn on such evidence?
In Cannings,** where three of the defendant’s four children had died in infancy
for no apparent reason, the Court of Appeal held that, where there was serious
disagreement between experts as to the cause of an infant’s death, and where
natural causes cannot be excluded as a reasonable (and not fanciful possibility),
the parent should not be prosecuted absent any evidence of deliberate harm to the
child in addition to the expert evidence.** However, in Kai-Whitewind® the Court
of Appeal held that Cannings was not authority for the proposition that whenever
there is a genuine conflict of opinion between reputable experts, the prosecution
should not proceed or that the evidence of the prosecution expert should be
disregarded. The Court said that Cannings did not reveal any new principle of
law or approach:
“it is no more than an example of the judge’s general obligation to ensure that the
case, however it is put, proceeds on a logically justifiable basis, and is not left to the
jury unless the evidence, taken at its highest, is such that the jury properly directed
could convict.”*°
In Harris*’ the Court of Appeal heard together four separate “shaken baby
syndrome”, or otherwise called, non-accidental head injury cases involving very
complex medical evidence. The appeal turned on research that demonstrated that
the long-held medical opinion of the conventional signs giving rise to inferences
of unlawful assaults on infants and very young children were unreliable. The
Court held that the cases demonstrated that instances of alleged non accidental
head injury were fact specific and had to be determined on their own facts.
Moreover, the Court reminded judges, practitioners and experts of the guidance
concerning expert witnesses provided in National Justice Cia Naviera SA v
Prudential Assurance Co Ltd®* (see para.6-35, below) and in re AB (Child Abuse:
Expert Witnesses)*°® which were said to be very relevant to criminal proceedings.
In re AB, Wall J gave helpful guidance for experts giving evidence involving
children. It was acknowledged that there will be cases of genuine disagreement
on a scientific or medical issue, or where it is necessary for a party to advance a
particular hypothesis to explain a given set of facts. Where that occurs in criminal
cases the jury will have to resolve the issue raised. To assist them:
8 Cannings [2004] 2 Cr.App.R. 63(7).
8 A similar approach was taken in Anthony [2005] 5 Archbold News 2 and Gay and Gay [2006] 5
Archbold News 1.
85 Kai-Whitewind [2005] 2 Cr.App.R. 31(73).
8 As set out in the well-known test in Galbraith (1981) 73 Cr.App.R. 124.
® Harris [2006] 1 Cr.App.R. 55(5).
88 National Justice Cia Naviera SA v Prudential Assurance Co Ltd [1993] Lloyd’s Rep. 68.
8 4B (Child Abuse: Expert Witnesses) Re [1995] 1 F.L.R. 181.
115
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(1) The expert who advances such a hypothesis owes a very heavy duty to
explain to the court that what he is advancing is a hypothesis, that it is
controversial (if it is) and place before the court all material which
contradicts the hypothesis.
(2) He must make all his material available to the other experts in the case. It is
the common experience of the courts that the better the experts the more
limited their areas of disagreement, and in the forensic context of a
contested case relating to children, the objective of the lawyers and the
experts should always be to limit the ambit of disagreement on medical
issues to the minimum.
In hearing the appeal of three joined shaken baby syndrome cases in
Henderson,° the Court of Appeal gave detailed guidance on the case
management of expert evidence and the content of the summing up regarding
such evidence. The Court emphasised the importance of the pre-trial phase in
cases where juries are required to evaluate complex medical evidence. The jury
could only approach conflicting expert evidence if it was marshalled and
controlled before it was presented to the jury. Thus, the judge dealing with the
pre-trial hearings should have experience of the complex issues and understand-
ing of the medical learning and also go on to hear the case. The Court drew
particular attention to the Kennedy Report on “Sudden unexpected death in
infancy”*! which recommended a checklist of matters to be established by the
trial judge before expert evidence was admitted, including: (i) whether the
proposed expert is still in practice; (ii) the extent to which he is an expert in the
subject to which he testifies; (iii) when he last saw a case in his own clinical
practice; and (iv) the extent to which his view is widely held. The Court also
referred to the importance of Part 33 of the Criminal Procedure Rules 2014°? (see
para.14—50, below) to ensure that the overriding objective to deal with criminal
cases justly was achieved. The jury should be given a detailed guide as to how to
approach conflicting expert evidence and the summing up should stress to the
jury that they should not convict unless the evidence led to the exclusion of any
realistic possibility of an unknown cause. Moreover, special caution is required
where the prosecution case heavily relied on developing medical science.
Cases of obscenity. The general rule is that expert evidence is not admissible
to prove that material is obscene under the Obscene Publications Act 1959, i.e.
whether it tends to deprave and corrupt the class of persons likely to read it.°? The
issue whether it has that tendency is for the jury to decide. The rationale of the
9% Henderson [2010] 2 CrApp.R. 24.
°1 ‘The Report of a working group convened by the Royal College of Pathologists and the Royal
College of Paediatrics and Child Health, published September 2004.
® With effect from 5 October 2015, the Criminal Procedure Rules 2015 (SI 2015/1490) revoke and
replace the 2014 rules (as amended). The rules will be substantially reorganised and reduced from 76
to 50 parts, Part 33 will become Part 19 and is amended to clarify the extent of an expert’s duty to the
court.
% Calder & Boyars Ltd [1969]1 Q.B. 151; Anderson [1972] 1 QB. 304 at 313; ef. Post Office Act
1953 s.11; Stamford [1972] 2 Q.B. 391.
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rule is that the jury has been given the responsibility of making the decision as
representing the ordinary man. It should not, therefore, be taken away from the
jury and given to experts.**
However, there may be cases where expert evidence is admissible because it is
not aimed at establishing that material has a tendency to deprave and corrupt, but
at providing information to assist the jury to decide whether it has such a
tendency. Thus, in Skirving and Grossman® the defendants were charged with
having an obscene article for publication for gain. The article was a pamphlet
concerned with the different ways of taking cocaine. The Court of Appeal held
that expert evidence relating to the taking of cocaine had rightly been admitted
because the expert was not usurping the function of the jury but informing them
of something which they could not be expected to know, i.e. the effects of taking
cocaine.
There may be an exception to the rule if the material is to be read by an
exceptional class of reader, “such that a jury cannot be expected to understand the
likely impact of the material upon its members without assistance”.°° In DPP v A.
& B.C. Chewing Gum Ltd,°’ the Divisional Court held that evidence from a
psychiatrist was admissible as to the effect of certain “battle cards” upon the
minds of children aged from five years upwards. The reason for the decision was
that while an adult jury is perfectly capable of considering the effect of something
on an adult, the jury or justices need help when considering the effect upon
children.°*
The correctness of the decision has been doubted, but it has not been
overruled. But there must be doubt whether there is sufficient cogency in the
reason given by the court to justify such a departure from principle. Most parents
do not need assistance from an expert on the question whether material was likely
to deprave and corrupt children.
Section 4(2) of the Obscene Publications Act 1959 provides that expert
evidence is admissible to establish or negative the defence’ that publication of
an obscene article is for the public good on the grounds that it is in the interests of
science, literature, art, or learning or other subjects of general interest. However,
that evidence is to be limited to “the literary, artistic, scientific or other merits” of
the articles.!°! It does not extend to evidence that the publication of the obscene
material would be of therapeutic benefit to a minority of the public with certain
sexual tendencies or difficulties!®* or would tempt young people to read it,'° or
would promote sex education,'°*
Special measures directions. An expert witness may now give evidence in
connection with an application for a special measures direction under s.20(6)(c)
°* DPP v Jordan [1977] A.C. 699 at 717, per Lord Wilberforce.
°8 Skirving and Grossman [1985] Q.B. 819.
9% Jordan [1977] A.C. 699 at 718, per Lord Wilberforce.
7 4. & B.C. Chewing Gum Ltd [1968] 1 Q.B. 159.
%8 4. & B.C. Chewing Gum Ltd [1968] 1 Q.B. 159 at 164-165, per Lord Parker CJ.
%® Jordan [1977] A.C. 699 at 722, per Lord Dilhorne.
100 Provided by s.4(1) of the Obscene Publications Act 1959.
101 Obscene Publications Act 1959 s.4(2).
102 Jordan [1977] A.C. 699.
103 Sumner [1977] Crim.L.R. 614.
104 4t-Gen¥s Ref. (No.3 of 1977) (1978) 67 Cr.App.R. 393.
117
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of the Youth Justice and Criminal Evidence Act 1999. An expert may also give
evidence as to whether a witness is competent (s.54(5)), and can give sworn or
unsworn evidence (s.55(6)).
6-28 Credibility of witnesses. I Medical evidence may be called to show that a
witness through disease or defect or abnormality of mind is not capable of giving
true or reliable evidence. The House of Lords held in Toohey v Metropolitan
Police Commissioner!®° that such evidence was admissible. Lord Pearce stated
the principle thus:
“Medical evidence is admissible to show that a witness suffers from some disease or
defect or abnormality of mind that affects the reliability of his evidence. Such
evidence is not confined to a general opinion of the unreliability of the witness, but
may give all the matters necessary to show, not only the foundation of and reasons
for the diagnosis, but also the extent to which the credibility of the witness is
affected.”!°),
This principle appeared to have been extended by the decision of the Privy
Council in Lowery, above, para.6—21. However, the scope of this decision has
been considerably restricted by subsequent decisions.'°’ In Turner,'°* the Court
of Appeal said that the Court did not consider it “authority for the proposition that
in all cases psychologists and psychiatrists can be called to prove the probability
of the accused’s veracity”.'°° Thus, it will only be in an exceptional case that such
evidence will be admitted. For instance, it is not permissible for the prosecution
to call a psychiatrist or psychologist to give evidence as to why a witness’s
evidence should be accepted as reliable (unless the defence is calling a witness to
say that it is unreliable).!"° Thus in Pinfold'"' it was held that expert medical
evidence calling into question the reliability of a co-accused’s confession was
admissible even where no physical examination of the witness had been carried
out. Moreover, in H and X (Childhood Amnesia)''* expert evidence was admitted
to the effect that adults have an impoverished memory of events happening in
childhood before the age of seven and therefore a detailed memory of such events
is likely to be unreliable; adult memories of events in later childhood are usually
better. However, it was noted that it would only be in the most unusual
circumstances that expert evidence of childhood amnesia would be relevant and
admissible.
105 Toohey v Metropolitan Police Commissioner [1965] A.C. 595.
196 Toohey v Metropolitan Police Commissioner [1965] A.C. 595 at 609 (emphasis supplied by
author).
17 Turner [1975] Q.B. 834; Neale (1977) 65 Cr.App.R. 304; and Rimmer and Beech [1983]
Crim.L.R. 250.
108 Turner [1975] Q.B. 834.
109 Turner [1975] Q.B. 834 at 842. Attempts to call psychiatric evidence in circumstances where one
defendant blamed the other for an offence failed in Neale(1977) 65 Cr.App.R. 304 and Rimmer and
Beech{1983] Crim.L.R. 250. In both cases, the evidence was held not to be relevant.
11 Robinson (1994) 98 Cr.App.R. 370.
"Pinfold [2004] 2 Cr.App.R. 3 (3).
"2-H and X (Childhood Amnesia) [2006] 1 Cr.App.R. 195(10).
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EXCEPTIONS TO THE GENERAL RULE
Evidence of the assessment of the credibility of witnesses by means of a lie
detector machine (polygraph) has not been admitted in this country.''> There is no
reported authority on the subject and in the unreported case of Burnal and Moore
the Privy Council said that polygraph evidence should only be made admissible,
if at all, as a result of legislation based on full scientific and legal research.''*
However, such machines are now used to assist with risk assessment and as
investigative tool for known sex offenders as part of probation conditions.
Sections 28-30 of the Offender Management Act 2007 provide for lie detectors to
be used as part of the determination of licence conditions for someone released
from prison.'!> Section 30, however, expressly prohibits the use of such evidence
in criminal proceedings.
There is good reason for this. The admissibility of polygraph evidence in any
criminal trial bristles with difficulty. First, the evidence of the operator of the
machine concerning statements by a witness relating to any incident or offence
must be hearsay. Secondly, if a defendant seeks to introduce evidence of a test
which he has taken, he will be in contravention of the rule prohibiting previous
consistent statements.''© There are also practical difficulties since there are
doubts about the accuracy of the test. Thus, the Royal Commission on Criminal
Procedure concluded that the machine’s “lack of certainty from an evidential
point of view” told against its introduction in this country.'!? A yet more
fundamental objection to its introduction is that it would make considerable
inroads into the jury’s function of assessing the credibility of witnesses. It can
hardly be in the interests of justice that this important function be handed over to
a machine, the accuracy of which is in doubt.
Qualifications of experts. It is for the court to decide whether a witness is
qualified to give expert evidence or not. Such competence may have been derived
either from a course of study or from experience. Thus, a medical practitioner or
a scientist will give evidence of his qualifications and thereby establish his
expertise. On the other hand, the witness may be an expert, but not in the relevant
subject. In that case, his opinion will not be admissible. Thus a witness with
training in psychology was not allowed to give medical evidence.'!*
However, the expertise may be derived from experience and not formal study.
Such experience may have been gained in a trade or business, for example an
antique dealer. Alternatively, it may have been gained simply during the course of
work. Thus, an experienced police officer was allowed to give expert evidence as
to how an accident had occurred.'!° In Murphy'?° the Court of Appeal held that a
police officer could give evidence of any matter that was within his expertise and
13 For use of the polygraph in the US, see D.W. Elliott’s essay in Well and Truly Tried (1983) and for
its use in Israel see Harnon, “Evidence Obtained by Polygraph: an Israeli Perspective” [1982]
Crim.L.R. 340.
"4 Burnal and Moore unreported 28 April 1997 (“Polygraph Evidence in Jamaica—The Door Left
Ajar”, Broadbent, 62 Jo.Crim.L. 585).
"5 ‘The use of such machines was upheld in Corbett v Secretary of State for Justice and NOMS
[2009] EWHC 2671 (Admin).
'N6 See D.W. Elliott’s essay in Well and Truly Tried(1983) for a discussion of these difficulties.
"7 Cmnd. 8092 (1981), para.4~76.
"8 Mackenney (1983) 76 Cr.App.R. 271.
"9 Qakley (1979) 70 CrApp.R. 7.
"20 Murphy [1980] Q.B. 434.
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in Jbrahima'?' the long-standing deputy director of a national drug advice charity
should have been allowed to give expert evidence based on their substantial
experience in the area of drug use. In Clare and Peach'?? a police officer who had
made a lengthy study of a poor quality, confused video which purported to show
the defendants committing offences was allowed to give evidence as to what, in
his opinion, was happening on the video. As the court pointed out, the witness
was open to cross-examination and the jury, after proper directions and warnings,
would be free to accept or reject his assertions. Similarly, in Breddick'*> expert
identification from a person with specialist skills in enhancing and interpreting
video images was admissible despite it being of a non-technical nature. Even so,
the judge should have warned the jury to approach the evidence with caution due
to its “lack of scientific basis”.
6-31 On the other hand, ordinary experience is not sufficient to make a witness an
expert. Thus, the fact that a witness is a driver himself does not entitle him to give
an opinion as to whether another driver is unfit through drink.'** Likewise, in
Inch'> the Courts-Martial Appeal Court held that a medical orderly should not
have been allowed at a court-martial to give evidence of his opinion that a wound
was the result of a blow from an instrument and was not consistent with a clash of
heads: such evidence should have been given by a person qualified to provide a
medical opinion. There may, however, be occasions when the opinions of
amateurs are admissible. Thus, in Si/verlock'?° a solicitor was allowed to give
evidence as an expert on handwriting, having gained his experience during the
course of his practice. However, such circumstances must be rare. It must be very
doubtful if an amateur would now be allowed to give evidence on a subject when.
there are experts available.
In practice, provided (a) the subject is one on which expert evidence is
admissible'?’; and (b) the witness has specialised knowledge or experience of the
subject, the witness’s evidence will usually be admitted and questions as to his
qualifications then go to the weight of the evidence rather than its admissibil-
ity.!28 For instance, the Court of Appeal in Robb'?? held that a phonetician,
qualified by academic training and practical experience, was qualified to express
an opinion on voice identification, although he relied on a technique which had
minority support in his profession.
121 Tbrahima [2005] Crim.L.R. 887.
122 Clare and Peach [1995] 2 Cr.App.R. 333.
123. Breddick, Independent, 21 May 2001, [2001] EWCA Crim 984.
'24 Davies (1962) 46 CrApp.R. 292.
125 Inch (1990) 91 Cr.App.R. 51.
26 Silverlock (1894) 2 Q.B. 766. See para.6-10, above, for a discussion concerning the opinion of
non-experts as to handwriting.
127 ‘This does not apply to all topics. See para.6-18, above.
128 Law Reform Committee, 17th Report, Evidence of Opinion and Expert Evidence, Cmnd.4489,
para.19.
129 Robb (1991) 93 Cr.App.R. 161.
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EXCEPTIONS TO THE GENERAL RULE
(2) The expert as witness
In 2011 the Law Commission published a report dealing specifically with expert
evidence: Expert Evidence in Criminal Proceedings in England and Wales.'*°
The Report highlighted a concern that too much expert evidence is admitted in
criminal trials without adequate scrutiny because no clear test is applied to
determine whether the evidence is sufficiently reliable. Thus, the Report
recommended that there be a new reliability-based admissibility test for expert
evidence in criminal proceedings so as to result in the exclusion of unreliable
opinion evidence. The Report also raised concerns about whether advocates
always cross-examine experts effectively to reveal potential flaws in the experts’
methodology, data and reasoning. A draft Criminal Evidence Bill was attached to
the Report with an appendix setting out the reliability-based admissibility test to
be applied by judges. Expert opinion evidence would not be admitted unless it
was adjudged to be sufficiently reliable to go before a jury.
The Government accepted the Law Commission’s concern about problems
caused by the use of inappropriate or unreliable expert evidence.'*! However,
rather than create a statutory reliability test, the Government instead opted to
invite the Criminal Procedure Rule Committee to consider amending the
Criminal Procedure Rules to ensure that judges are provided with more
information about the expert evidence at an early stage in the initial proceedings.
Those proposed amendments were incorporated into the Criminal Procedure
Rules 2014'*, which came into force on October 6, 2014. The amendments seek
to clarify what information the court must have so as to be able to make an
informed decision about the admissibility of the evidence, having regard to the
reliability of the expert’s opinion and, where relevant, having regard to the
expert’s own credibility. Where evidence is likely to be in dispute, the rules now
provide for it to be introduced in the first instance in summary form, and a full
report will only be required if the conclusions are contested. Part 33 is further
amended by the Criminal Procedure Rules 2015'**, which come into force in
October 2015!**.
The Criminal Procedure Rules must now be read alongside new Criminal
Practice Direction (Evidence), 33A on expert evidence that also came into force
on October 6, 2014. The direction lists the factors that a court may take into
account in determining the reliability of expert opinion (especially of expert
scientific opinion), and identifies some of the potential flaws in such opinion,
which might deract from its reliability, that the court should be astute to identify.
In H.'* Lord Justice Leveson stated that following the changes made to the
Criminal Procedure Rules and the Criminal Practice Direction, advocates and the
130 Expert Evidence in Criminal Proceedings in England and Wales, 21 March 2011, Law Com.
No.325. Recommendations on expert evidence were previously made by the Royal Commission on
Criminal Justice, Cm.2263 [1993], Ch.9, and in the Auld Report, Review of the Criminal Courts of
England and Wales, 2001, pp.571-582.
31 The Government’ response to the Law Commission Report, 21 November 2013.
182 ST 2014/1610.
183. S] 2015/1490.
'54 For further detail on the restructuring and amendments to the Criminal Procedure Rules 2014, see
2.89, above.
135 [2014] Crim.LR. 905.
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courts must adopt a new and more rigorous approach to the handling of expert
evidence. In particular, comment based only on analysis of the evidence which
effectively usurped the task of the jury was to be avoided.
6-33 Compellability and privilege. I Expert witnesses are, like other witnesses,
compellable.'*° They may also be required to produce documents as the result of
a subpoena.'*’ There is no property in an expert witness. Therefore, if a
psychiatrist interviews a defendant in prison, he may be called as an expert by the
prosecution or defence. !**
Confidential communications between a solicitor and an expert are protected
by legal professional privilege.'*? There is, however, no privilege in relation to (i)
the documents or materials upon which the expert’s opinion is based; or (ii) the
independent opinion of the expert himself.'*° Thus, in King'*! the defence
solicitor had sent various documents to a handwriting expert for his opinion. The
prosecution served a subpoena on the expert requiring him to produce the
documents. The defence objected to the production of the documents on the
ground of privilege. The judge ruled that no privilege attached to the documents
and allowed the prosecution to call the expert to produce the documents. The
Court of Appeal upheld this ruling.
6-34 In many cases, the expert’s evidence is not in dispute and there is no need to
call him. In some cases, however, it may be essential to do so. Hipson'*? is an
example of such a case. An expert was called at the committal proceedings. He
said, without giving reasons, that in his opinion the handwriting on an
endorsement of a cheque was the defendant’s, He was conditionally bound as a
witness. His deposition was read at the trial, There was no other evidence against
the defendant. A submission of no case was refused. The subsequent appeal was
allowed on the ground that the undisputed evidence fell short of the required
standard of proof. The Court of Appeal said that in such cases the jury should
have the assistance of the expert witness in court in order to help them make a
decision as to the weight and reliability of the evidence.
6-35 Independence. The expertise and integrity of experts is fundamental to the
proper functioning of the criminal system. This point was stressed in Kumar v
GMA'* which concerned a consultant psychiatrist who gave evidence in a case
involving diminished responsibility without disclosing that he had no experience
as an expert in homicide cases. He was found guilty of misconduct by the GMC.
The expert’s duty to the court is set out in 1.33.2 of the Criminal Procedure
Rules 2014!**;
136 Harmony Shipping Co v Davis [1979] 3 AIL E.R. 177, CA. For the compellability of witnesses, see
Ch.17, below.
137 King (1983) 77 Cr.App.R. 1.
138 See, e.g. Smith (1979) 69 CrApp.R. 378.
‘39. Harmony Shipping Co [1979] 3 All E.R. 177 at 181, CA. For legal professional privilege, see
para.11-33, below.
140 Harmony Shipping Co [1979] 3 All E.R. 177 at 181, CA, per Lord Denning MR; King (1983) 77
CrApp.R. 1.
141 King (1983) 77 Cr.App.R. 1.
"2 Hipson 112 S.J. 945, [1969] Crim.L.R. 85.
‘43. Kumar v GMA [2013] ACD 25(10).
144 ST 2014/1610. As to the replacement and restructuring of the 2014 rules, see n.89, above.
122
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An expert must help the court to achieve the overriding objective by giving
opinion on matters which is—
(a) objective and unbiased; and
(b) within the expert’s area or areas of expertise.
This duty overrides any obligation to the person from whom the expert
receives instructions or by whom the expert is paid.
This duty includes obligations—
(a) to define the expert’s area or areas of expertise—
(i) in the expert’s report, and
(ii) when giving evidence in person;
(b) when giving evidence in person, to draw the court's attention to any
question to which the answer would be outside the expert's area or
areas of expertise; and
(c) to inform all parties and the court if the expert's opinion changes from
that contained in a report served as evidence or given in a statement.
The Court of Appeal in Harris'*° summarised the obligations of experts as
previously set out by Cresswell J in a civil case!'*°:
qd)
6)
(4)
(5)
(6)
Expert evidence presented to the court should be and seen to be the
independent product of the expert uninfluenced as to form or content by the
exigencies of litigation.
An expert witness should provide independent assistance to the court by
way of objective unbiased opinion in relation to matters within his
expertise. An expert witness should never assume the role of advocate.
An expert witness should state the facts and assumptions on which his
opinion is based. He should not omit to consider material facts which
detract from his concluded opinions.
An expert should make it clear when a particular question or issue falls
outside his expertise.
If an expert’s opinion is not properly researched because he considers that
insufficient data is available then this must be stated with an indication that
the opinion is no more than a provisional one.
If after exchange of reports, an expert witness changes his view of material
matters, such changes of view should be communicated to the other side
without delay and, when appropriate, the court.
147
In another civil case, Toth v Jarman,'*’ it was held that, so long as the opinion
of the expert witness is independent of the parties and the pressures of litigation,
the existence of a potential conflict of interest on his part does not automatically
diss
qualify them from giving expert evidence, nor is it a breach of art.6(1). In
Gokal'** an expert who was a member of the investigating team was not thereby
a5
146
a7
48
Harris [2006] 1 Cr.App.R. 5. This case was approved in Bowman [2006] 2 Cr.App.R. 3.
National Justice Cia Naviera SA v Prudential Assurance Co Ltd [1993] 2 Lloyd’s Rep. 68.
Toth v Jarman (2006) 4 All E.R. 1276.
Gokal [1999] 6 Archbold News 2.
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disqualified. Similarly, in Leo Sawrij v North Cumbria Magistrates Court,'*° the
evidence of an expert witness who had a commercial connection with the party
calling him was held admissible.
6-36 Expert reports. Section 30 of the Criminal Justice Act 1988 provides that a
report by an expert is admissible as evidence in criminal proceedings of any fact
or opinion of which the expert could have given oral evidence. This is so,
whether or not the expert gives evidence. But if he is not to give oral evidence,
the leave of the court is required before his report is admitted. The section defines
in “expert report” as a written report by a person dealing wholly or mainly with
matters on which he is or would, if living, be qualified to give expert evidence.
The section provides that in determining whether to give leave, the court shall
have regard to the contents of the report; the reason why it is proposed that the
expert shall not give oral evidence; the risk, having regard in particular to
whether it is likely to be possible to controvert statements in the report without
oral evidence, of unfairness to the accused; and any other relevant circumstances.
Accordingly, if the expert gives evidence, his report is admissible as evidence
of the facts and opinions stated in it. This means that the court and jury can have
copies of the report while the expert is giving evidence. It is thus possible to
avoid the laborious process of the expert reading out his report when giving
evidence. He can simply produce his report and be cross-examined upon it.
6-37 Whether leave is granted for the report to be admitted when the expert does
not give evidence depends on the circumstances of the particular case. The court
must consider all the matters set out in the section. In some cases it may be proper
to admit the report without oral evidence because its contents are not in dispute or
not substantially in dispute. On the other hand, in most cases where there is a
substantial dispute about the contents, it is difficult to see how it will be possible
properly to controvert the statements in the report unless the maker gives oral
evidence and is cross-examined. It may be said that the statements can be
controverted by other evidence. However, the jury will not be able to assess the
evidence properly unless they have seen the expert cross-examined on his report.
6-38 Preparatory work. Before the coming into effect of s.127 of the Criminal
Justice Act 2003 an expert was not permitted to give an opinion based on
scientific facts run by assistants unless all those assistants were called upon to
give supporting evidence in court.'*° This situation could in theory affect all such
evidence since experts almost invariably depend on primary facts provided by
machines or derived from the evidence of others or from their own earlier
observations!>! and had considerable potential for the waste of public time and
money, !5?
“49 Leo Sawrij v North Cumbria Magistrates Court [2010] 1 Cr.App.R. 304(22).
150 Report of the Royal Commission on Criminal Justice, Cm.2263 (1993), para.9.78, quoted Law
Commission Report, “Evidence in Criminal Proceedings: Hearsay and Related Topics”, Law Com.
No.245, 1997, para.9.1. The situation was also criticised in the Law Commission Consultative Paper
No.138, 1995, “Evidence in Criminal Proceedings: Hearsay and Related Topics”.
151 Morland J in Galizadeh [1995] Crim.L.R. 232.
182 Tllustrated by Jackson [1996] Crim.L.R. 732, Law Com. Rep. at para.9.11. At the time of writing,
the section is expected to come into effect in April 2005.
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The position has now been rectified by s.127 of the 2003 Act as follows. An
expert giving evidence in criminal proceedings may base an opinion or inference
on a statement prepared by another person for the purposes of criminal
proceedings or a criminal investigation.'*> That person must have, or be
reasonably supposed to have had, personal knowledge of the matters stated,'**
and notice must be given that the expert will be basing his opinion or inference on
that statement.'**
Such a statement is to be treated as evidence of what it states,'*° but the court
may, if applied to by one of the parties to the proceedings, order in the interests of
justice that the statement not be admitted.'*” In deciding whether or not to call the
original maker of statement, the court should take into consideration the expense
of calling the statement maker, whether he could give relevant evidence which
the expert could not, and whether he could reasonably be expected to remember
the matters stated well enough to give oral evidence of them.'**
Contents of expert’s report. The required contents of any expert’s report are
now set out in r.33.4 of the Criminal Procedure Rules 2014'*° which states that an
expert’s report must:
(a) give details of the expert’s qualifications, relevant experience and
accreditation;
(b) give details of any literature or other information which the expert has
relied on in making the report;
(c) contain a statement setting out the substance of all facts given to the expert
which are material to the opinions expressed in the report, or upon which
those opinions are based;
(d) make clear which of the facts stated in the report are within the expert’s
own knowledge:
(e) say who carried out any examination, measurement, test or experiment
which the expert has used for the report and—.
(i) give the qualifications, relevant experience and accreditation of that
person,
(ii) say whether or not the examination, measurement, test or experiment
was carried out under the expert’s supervision, and
(iii) summarise the findings on which the expert relies;
(f) where there is a range of opinion on the matters dealt with in the report—
(i) summarise the range of opinion, and
(ii) give reasons for the expert’s own opinion;
(g) if the expert is not able to give an opinion without qualification, state the
qualification;
'S Criminal Justice Act 2003 s.127(1)(a), (2), (6).
'S4 Criminal Justice Act 2003 s.127(1)(b).
'55 Criminal Justice Act 2003 s.127(1)(c); “under the appropriate rules” as to advance evidence: by
subs.(7). No such rules have been made to date.
156 Criminal Justice Act 2003 s.127(3).
157 Criminal Justice Act 2003 s.127(4).
'S8 Criminal Justice Act 2003 s.127(5).
'S $1 2014/1610. As to the replacement and restructuring of the 2014 rules, see n.89, above.
125
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(h) include such information as the court may need to decide whether the
expert’s opinion is sufficiently reliable to be admissible as evidence;
(i) contain a summary of the conclusions reached;
(j) contain a statement that the expert understands an expert’s duty to the court,
and has complied and will continue to comply with that duty; and
(k) contain the same declaration of truth as a witness statement.
The Court of Appeal has stressed the importance of complying with these
obligations: Reed and Reed'® and C.'°!
Disclosure of expert evidence.
Advance notice. Rule 33.3 of the Criminal Procedure Rules 2014'° sets out the
procedure for admitting a summary of an expert’s conclusions and states that the
summary must be served on both the court and each party from whom that
admission is sought as soon as practicable after the defendant whom it affects
pleads not guilty. Where more than one party wants to introduce expert evidence,
1.33.6 provides that the court may direct the experts to discuss the issues in the
proceedings and prepare a statement for the court on the matters upon which they
agree and disagree (with their reasons). Where more than one defendant wants to
introduce expert evidence on an issue at trial, the court may direct that the
evidence on that issue be given by only one expert thereby requiring the
co-defendants to agree upon a single expert: 1.33.7.
A party who fails to disclose expert evidence is not permitted to adduce it
without leave of the court. In deciding whether to give leave, the court will be
required to exercise its discretion by balancing the interests of the public
represented by the Crown and the interests of the defendant. The result may be
that it is necessary to admit evidence (albeit at the last minute) because of its
importance in relation to the issues in the trial. On the other hand, if the defence
keeps expert evidence to itself and then seeks to “ambush” the prosecution it is
likely to be excluded. See for example: Ensor'® and Reed and Reed.'**
The purpose of these rules is to ensure that a party is not taken by surprise by
expert evidence being adduced without notice at trial. In particular, the
prosecution is thus afforded an opportunity to evaluate any such evidence and
thereby avoid the delay which may be occasioned by an adjournment to consider
evidence during the trial. If delay is occasioned in these circumstances a “wasted
costs” order may appropriately be made against the party responsible.
Section 20(3) of the Criminal Procedure and Investigations Act 1996 permits
similar rules relating to the disclosure of expert evidence as apply to trials on
indictment (under s.81 of the Police and Criminal Evidence Act 1984) in
magistrates’ courts, and the Criminal Procedure Rules 2014 also apply to
summary trials.'°° Such a provision is to be welcomed as lessening the
169 Reed and Reed [2010] 1 Cr.App.R. 23.
16! © [2011] 3 AIL ER. 509.
16 S$] 2014/1610. As to the replacement and restructuring of the 2014 rules, see 0.89, above.
163 Ensor [2010] 1 Cr.App.R. 18.
164 Reed and Reed [2010] 1 Cr.App.R. 23.
'65 The rules which have been issued are the Magistrates’ Courts (Advance Notice of Expert
Evidence) Rules 1997 (SI 1997/533).
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EXCEPTIONS TO THE GENERAL RULE
opportunity for “trial by ambush” by springing expert evidence on the other party
with the consequent unfairness and the potential for waste of time if an
adjournment has to be granted for the other party to meet the evidence.
Unused material. There is a requirement that forensic scientists make full
disclosure of unused material: Ward.'°° The duty extends to anything casting
doubt on the scientists’ opinions and includes anything that might arguably assist
the defence. It exists irrespective of requests by the defence. The Royal
Commission on Criminal Justice!®’ interpreted the decision to mean that, if
expert witnesses are aware of experiments or tests (even if not carried out by
them), they are under an obligation to bring the records of the experiments to the
attention of the police and prosecution.
As to disclosure of unused material, see further generally paras 18-05 to
18-30.
Written material, experiments, personal experience. Experts, when giving
evidence of opinion, may make reference to text books and other material written
in their field of expertise. The material does not have to be in published form.'®*
The Law Reform Committee summarised the principle succinctly. “Experts may
refer to a text book or other written material if it is regarded as authoritative by
those qualified in their speciality.”'© It is obviously essential that experts should
be allowed to refer to such written material in order to give authority for their
opinions and keep abreast with developments in the subject of their expertise.
The expert may thus rely on the accepted work of others. He may rely on
experiments conducted by others. He is not required to have conducted an
experiment himself in order to make his evidence about it admissible. Thus, a
doctor may refer to recognised tables relating to the rates of conversion and
destruction of alcohol in the body, although he himself has not conducted the
experiments on which the tables are based.'7° The fact that he himself has not
made the experiments maygo to the weight of the evidence: it does not go to
admissibility.'7!
Similarly, the expert may rely on statistics collated by others. In Abadom
the Court of Appeal held that an expert was entitled to rely on statistics of the
refractive index of broken glass collated by the Home Office in giving his
opinion that glass samples found on the defendant’s shoes came from a window
broken during the course of an armed robbery. It was argued in Abadom that the
evidence based on the statistics was hearsay and therefore inadmissible. The
Court rejected this argument because (a) it was inevitable that such statistics
would result from the work of others; and (b) to exclude reliance upon such
information would lead to the distortion of unreliability of the expert’s opinion.
172
6 Ward (1992) 94 Cr.App.R. 1. Also Maguire (1992) 94 Cr.App.R. 133.
7 Cm.2263 (1993), paras 9-46 to 9-48.
8 Abadom (1983) 76 Cr.App.R. 48.
1 Law Reform Committee, 17th Report, Evidence of Opinion and Expert Evidence, Cmnd.4489,
para.20. The same rule applies to professional practice: see Smith(1974) 58 Cr.App.R. 106.
17 Somers (1963) 48 Cr.App.R. 11.
71 Somers (1963) 48 Cr.App.R. 11.
72 Abadom (1983) 76 Cr.App.R. 48.
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If the expert does rely on such information (whether published or unpublished)
he should refer to the material in his evidence so that his opinion can be assessed
by reference to it.!7>
An expert may also rely on his own experience. Thus, in Hodges and
Walker,'”* the evidence of an experienced drugs officer as to the method of the
supply of heroin, the local purchase price and that a certain amount would have
been more than would have been used for personal use was rightly admitted as
expert evidence. This was consistent with the approach outlined in Bonython'”*
and was of the type envisaged in Abadom.'7°
(3) Proving facts upon which expert opinion is based
There is a distinction in the evidence given by experts between (i) evidence of
fact, for example the characteristics of a fingerprint; and (ii) evidence of opinion,
i.e. inferences drawn from certain facts.
In the former case the expert gives evidence of his own findings and the facts
are thereby proved. In this case the person who carried out any work upon which
such findings are based must himself give evidence. Thus, if it is to be proved
that the blood found in some stains was of a similar grouping to that of the
defendant, the forensic scientist who carried out the tests to establish the grouping
must be called. If another scientist were to give evidence of the tests (which he
had not himself carried out), that evidence would be hearsay and inadmissible.
In the latter case ((ii) above) the expert must, in giving his opinion, rely on
certain facts. These facts must be proved in the trial by admissible evidence.'””
Furthermore, the witness should state the facts upon which his opinion is based.
The Court of Appeal has said that the witness should do this in examination-in-
chief.'"* The jury will thereby discover whether the witness has been correctly
informed about the facts, and has taken the relevant facts into consideration. The
jury will then be in a position to assess the witness’s evidence properly.
The witness’s statement of facts may lead to the introduction of some
second-hand evidence, for example a doctor may rely upon what a patient has
told him. This will not be hearsay since, whether true or false, it is merely part of
the information upon which the doctor’s opinion was formed.'’? Thus, the Court
of Appeal in Bradshaw'* said that a doctor may not state what a patient told him
about past symptoms as evidence of those symptoms because that would infringe
the rule against hearsay, but he may give evidence as to what the patient told him
in order to explain the grounds on which he came to a conclusion with regard to
the patient’s condition.
173 Abadom (1983) 76 Cr.App.R. 48 at 52-53.
'74 Hodges and Walker (2003] Crim.L.R. 472.
175 Bonython (1984) 38 S.A.S.R. 45.
176 Abadom (1983) 76 Cr.App.R. 48.
177 Abadom [1983] 1 W.L.R. 126, (1983) 76 Cr.App.R. 48, applying dicta in English Exporters
(London) Ltd v Eldonwall Ltd [1973] Ch. 415 at 421, per Megarry J and Turner [1975] 1 Q.B. 834 at
840. See also Hodges and Walker [2003] Crim.L.R. 472; para.6-45, above.
178 Turner [1975] 1 Q.B. 834 at 840.
179 Wigmore, A Treatise on the Anglo-American System of Evidence (3rd edn, 1940), vol.vi,
para.1320 quoted in Pattenden, “Expert Opinion Evidence on Hearsay” [1982] Crim.L.R. 85 at 87.
180 Bradshaw (1985) 82 CrApp.R. 79 at 83.
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The facts may be proved by the expert himself. Thus, the fingerprint expert
will give evidence of his findings of similarity in “ridge” characteristics between
the defendant’s fingerprint and that found at the scene of the crime. In giving
evidence the expert produces the materials on which he has worked, for example
blown-up photographs of fingerprints or handwriting samples. He can then
demonstrate how he has arrived at his opinion. He can also be cross-examined
about both the opinion and his materials. Indeed, in the absence of the materials,
it may not be possible for the jury to see how the expert arrived at his opinion. In
a case where an expert gave evidence about voice identity, the Court of Appeal
held that a judge was wrong to have excluded the tapes on which the expert’s
opinion was based.'*!
The facts must be proved, if not by the expert, then by someone else, as, for
instance, when the finding of a fingerprint at the scene of crime is proved by
another witness such as the Scenes of Crime Officer. If the facts are not proved,
the opinion of the expert is worthless. Where the expert relies on facts which are
not proved by him, it is for the prosecution (or the party calling the expert) to fill
the evidential gap.'*? Once the facts have been proved by admissible evidence,
experts are “entitled to draw on the work of others as part of the process of
arriving at their conclusion”.'*?
(4) Function and weight of expert evidence
The function of expert evidence is to assist the court by providing information
which is outside the experience and knowledge of the judge or jury. The expert’s
function in giving his opinion is to assist the jury in the interpretation of evidence
where such evidence might not otherwise be intelligible to them. (In Clarke'** the
evidence concerned was facial mapping by way of video superimposition: the
court pointed out that this new, and valuable, crime detection technique was just
as much evidence as blown-up photographs of fingerprint evidence.) On the other
hand, questions relating to the weight of the evidence are for the jury to
determine. These issues involve the consideration of two apparently conflicting
principles.
The first principle is that the expert does not decide the case. He assists the
jury or justices to do so. This principle was stated by Lord President Cooper:
“[The duty of the expert witness] is to furnish the Judge or jury with the necessary
scientific criteria for testing the accuracy of their conclusions, so as to enable the
Judge or jury to form their own independent judgment by the application of these
criteria to the facts proved by the evidence. The scientific opinion evidence, if
intelligible, convincing and tested, becomes a factor (and often an important factor)
for consideration along with the whole other evidence in the case.”'**
81 Bentum (1989) 153 J.P. 538.
82 Jackson [1996] 2 Cr.App.R. 420.
3 Abadom (1983) 76 Cr.App.R. 48 at 52.
184 Clarke [1995] 2 Cr.App.R. 425. Facial mapping is now an accepted form of evidence: Atkins (D &
‘M) [2009] Crim. LR. 141.
85 Davie v Edinburgh Magistrates, 1953 S.C. 34, 40.
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Thus, the fact that an expert says that in his opinion, fingerprints found at the
scene of a burglary were made by the defendant, does not, itself, decide the
defendant’s guilt. It is for the jury to say whether he is guilty or not.
The jury must also be allowed to decide what weight to give to the expert’s
evidence. While it is important to direct the jury that they were not bound by an
expert’s opinion, the direction need not be given in a particular way (such as that
promulgated in the Crown Court Bench Book and Specimen Directions)'**:
Fitzpatrick (Gerald).!*’ Nor should the jury be directed that the evidence of an
expert ought to be accepted as it gives a misleading impression of the weight of
the evidence.'** A further example is to be found in the defence of insanity. This
is an issue for the jury to decide. In Rivett,!*° the Court of Criminal Appeal would
not interfere with a verdict of guilty despite medical evidence that the defendant
was insane.
The second principle is that if there is nothing to contradict the expert’s
evidence the jury should accept it. For example, it was held to be a misdirection
to invite the jury to disregard the uncontradicted evidence of an expert that there
was no blood on certain boots and to substitute their own opinion.!° Similarly, if
there is uncontradicted medical evidence in support of a defence of diminished
responsibility, the jury should not reject it, and convict of murder. In Matheson'*!
and Bailey'®? there was uncontradicted medical evidence to this effect, but the
jury convicted of murder. In both cases the Court of Criminal Appeal substituted
verdicts of manslaughter. The rationale for these decisions is to be found in the
judgment of Lord Goddard CJ in Matheson:
“While it has often been emphasised and we would repeat, that the decision in these
cases, as in those in which insanity is pleaded, is for the jury and not for the doctors,
the verdict must be founded on evidence. If there are facts which would entitle a
jury to reject or differ from the opinions of the medical men, the court would not,
and indeed could not, disturb their verdict, but if the doctor’s evidence is
unchallenged and there is no other on this issue, a verdict contrary to their opinion
would not be ‘a true verdict in accordance with the evidence’.”!°°
On the other hand, in Walton v The Queen,'** the Privy Council held that a
jury was entitled to reject the uncontradicted evidence of a psychiatrist in support
of a defence of diminished responsibility when:
(a) the quality and weight of medical evidence fell a long way short of that in
Bailey and Matheson;
(b) evidence of the conduct of the defendant at the time of the killing did not
indicate a person bordering on insanity; and
186 Crown Court Bench Book and Specimen Directions (3rd edn, 2010).
'87 Fitzpatrick (Gerald) [1999] Crim.L.R. 832.
188 Lanfear (1968) 52 Cr.App.R. 176.
189 Rivet (1950) 34 Cr.App.R. 87.
190 Anderson [1972] A.C. 100.
191 Matheson [1958] 1 W.L.R. 474.
192 Bailey (1978) 66 CrApp.R. 31.
'93 Matheson [1958] 1 W.L.R. 474 at 478 (emphasis supplied by author).
194 Walton v The Queen [1978] A.C. 788.
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(c) there was no objective evidence of a history of mental disorder on the part
of the defendant.
Reconciling these cases is not easy; but the position may be summarised in
this way:
(a) _ if the expert evidence is clear and uncontradicted by any other evidence, the
jury should accept it.
(b) If, however, the evidence is not clear or there is evidence which tends to
contradict the expert’s opinion, the jury may reject it.
Where two or more expert witnesses give evidence for opposing sides, the
direction to the jury should be to convict only if it is satisfied beyond reasonable
doubt that it should accept the expert evidence adduced by the prosecution and
reject that adduced by the defence. Accordingly, a direction to the jury to decide
on the balance of probabilities is wrong.'*> In Leon'®® it was reiterated that
particular care must be taken when summing-up in a case in which experts have
disagreed. A clear and fair summary of each party’s expert evidence with an
appropriate direction as to how to approach such evidence must be given. The
summing up should not simply repeat the evidence of the experts, the evidence
should rather be summarised issue by issue and in such a way that the summing
up will make it easier to understand how a verdict has been reached:
Henderson.'°"
195. Platt [1981] Crim.L.R. 332.
196 Leon [2009] R.T.R. 26. See also Hookway and Noakes [2012] Crim.L.R. 130—where DNA
experts disagreed it is for the jury to determine the weight to be given to each expert.
'97 Henderson [2010] 2 Cr.App-R. 24. For the suggested approach in DNA cases, see Doheny and
Adams{1997} 1 Cr.App.R. 369.
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