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The Law Commission’s Consultation: Specific Issues
To help you get to grips with the specific issues raised by the Law Commission in its Consultation Paper, this section lists the issues in which
the Law Commission is particularly interested, together with some background information
and key considerations for each issue. We have tried to avoid biasing the
information in this section towards our own views (which you can
read in the
section if you wish).
After reading this, you can:
Paragraph 6.78
Do consultees agree with our provisional proposal that there should be a statutory
test for the admissibility of expert evidence in criminal proceedings, as follows?
(1) The opinion evidence of an expert witness is admissible only if the
court is satisfied that it is sufficiently reliable to be admitted.
(2) The opinion evidence of an expert witness is sufficiently reliable to
be admitted if:–
(a) the evidence is predicated on sound principles, techniques
and assumptions;
(b) those principles, techniques and assumptions have been
properly applied to the facts of the case; and
(c) the evidence is supported by those principles, techniques and assumptions as applied to the facts of the case.
(3) It is for the party wishing to rely on the opinion evidence of an expert witness to show that it is sufficiently reliable to be admitted.
Consider...
- Is the Law Commission right to seek to tighten up the controls on the expert evidence that can be placed before a jury in a criminal trial?
- Does the adversarial system fail to expose poor-quality (unfounded) expert evidence?
- How easy would it be for you to demonstrate that your evidence was sound?
- Is there any element required to determine the reliability of expert evidence other than the three-stage scheme set out in 2a-c?
- Is it right for the onus to be on those who propose to adduce evidence to have to prove its reliability - or does this go against the usual practice of the defence only having to introduce reasonable doubt?
- Have you any examples of cases where such a power would have prevented, or not have been able to prevent, a miscarriage of justice?
Paragraph 6.79
Do consultees agree with our provisional proposal that trial judges should be
provided with guidelines for determining the evidentiary reliability of scientific (or
purportedly scientific) expert evidence, as follows?
(1) In determining whether scientific (or purportedly scientific) expert evidence is sufficiently reliable to be admitted, the court shall consider the following factors and any other factors considered to
be relevant:
(a) whether the principles, techniques and assumptions relied on have been properly tested, and, if so, the extent to which
the results of those tests demonstrate that they are sound;
(b) the margin of error associated with the application of, and conclusions drawn from, the principles, techniques and assumptions;
(c) whether there is a body of specialised literature relating to the field;
(d) the extent to which the principles, techniques and
assumptions have been considered by other scientists – for
example in peer-reviewed publications – and, if so, the extent to which they are regarded as sound in the scientific community;
(e) the expert witness’s relevant qualifications, experience and publications and his or her standing in the scientific community;
(f) the scientific validity of opposing views (if any) and the
relevant qualifications and experience and professional standing in the scientific community of the scientists who hold those views; and
(g) whether there is evidence to suggest that the expert witness has failed to act in accordance with his or her overriding duty of impartiality.
Consider...
- Do these steps work in practice for your specialism?
- Could you provide the necessary proof?
- How much extra time would it take you to put together such a body of evidence?
- Would you have to repeat this exercise for each case or would it be essentially a one-off task?
- Is peer-review relevant?
- Would these steps bar any particular types of evidence?
- How would you demonstrate your standing in your scientific community?
- How scientifically competent would the judge have to be to understand the evidence you would put forward as demonstrating the reliability of the body of knowledge from which your evidence is drawn?
- How easily can you separate your science-based opinions from your experienced-based opinions?
Paragraph 6.80
Do consultees agree with our provisional proposed guidelines for experience-based
(non-scientific) expert evidence, as follows?
(1) In determining whether experience-based expert evidence is
sufficiently reliable to be admitted, the court shall consider the
following factors (where applicable) and any other factors
considered to be relevant:
(a) the expert’s qualifications, practical experience, training and
publications and his or her standing in the professional or
other expert community;
(b) the extent to which the basis and validity of the expert’s
opinion can be explained, with particular reference to:
(i) the extent to which the basis of the opinion (for
example, any assumption relied upon) has been
verified or discredited;
(ii) the specific instances which support the claim to
experience-based expertise;
(iii) the bearing those instances have on the matter(s) in
issue; and
(iv) whether the expert’s methodology or reasoning has
previously resulted in a demonstrably valid or
erroneous opinion;
(c) whether there is a body of specialised literature relating to
the field of expertise and, if so:
(i) the extent to which it supports or undermines the
expert’s methodology and reasoning; and
(ii) the extent to which the expert’s methodology and
reasoning are recognised as acceptable amongst his
or her peers;
(d) whether there is evidence to suggest that the expert has
failed to act in accordance with his or her overriding duty of
impartiality.
Consider...
- Do these steps work in practice for your specialism?
- Could you provide the necessary proof?
- How much extra time would it take you to put together such a body of evidence?
- Would you have to repeat this exercise for each case or would it be essentially a one-off task?
- Would these steps bar any particular types of evidence?
- How would you demonstrate your standing in your expert community?
- How aware of your profession would the judge have to be to understand the evidence you would put forward as demonstrating the reliability of the body of knowledge from which your evidence is drawn?
Paragraph 6.81
Do consultees agree with our provisional proposal that,
where necessary, the party proposing to adduce expert evidence, whether the
prosecution or a defendant, should have to demonstrate that it is sufficiently reliable
to be placed before the jury?
Consider...
- Is it right for the onus to be on those who propose to adduce evidence to have to prove its reliability? Or does this go against the usual practice of the defence only having to introduce reasonable doubt?
- Is there a need for the opposing side to be able to challenge the evidence
put forward?
Paragraph 6.82
Do consultees agree with our view that the other aspects of the present common
law test governing the admissibility of expert evidence in criminal proceedings are
satisfactory? (See below.) If so, do
consultees believe that these rules should be codified in primary legislation?
1.2.1 whether the subject matter of the opinion is such that a person without instruction or experience in the area of knowledge or human experience
would be able to form a sound judgment on the matter without the assistance of a witness possessing special knowledge or experience in the area
1.2.3 whether the witness has acquired by study or experience sufficient knowledge of the subject to render his opinion of value in resolving the issues before the court
1.3 A fourth requirement is that that the expert must be capable of providing an impartial
opinion, in recognition of the fact that an expert’s overriding duty is to the court and not the party calling him or her to testify.
We make no comment on this. Paragraph 6.83i
We would also welcome consultees’ views on whether the trial judge should, in exceptional cases, be entitled to call
upon an independent assessor to help him or her apply our proposed test
for determining the reliability of expert evidence.
Consider...
- The Criminal Rules Committee chose not to import the assessor role from the Civil Procedure Rules. If it wasn't right then is it right now?
- Have you any experience of a civil court using a court assessor under CPR 35.15?
- Would it be right to have a third expert introduced?
- Would such an expert tend to become more powerful than any other expert in the case?
Paragraph 6.83ii
We would also welcome consultees’ views on whether the question of evidentiary reliability should always be decided
before the jury is sworn, with the possibility of an interlocutory appeal to
the Court of Appeal.
Consider...
- Is it right to have some earlier exploration of the expert evidence in a criminal trial?
- Is it acceptable for the court to decide on such matters before the jury has had the chance to hear the evidence? Should it be left to the jury to decide?
- Should the jury be told about the outcome of the early assessment of reliability, or can they take it as read that any expert evidence they do hear will be de facto reliable?
- Have you taken part in trials where the evidence adduced at the trial was significantly different from that you thought you would give?
What next?
You can now:
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