THE INSTRUCTION OF EXPERTS : LOOKING AT GUIDANCE FROM THE CROWN PROSECUTION SERVICE

I have written before the useful guidance given by the Crown Prosecution Guidance on Expert Evidence.  Many of the points in that guide apply, with equal force, to instructing experts in civil proceedings. It is worthwhile reading for lawyers and experts alike, its usefulness is not confined to criminal cases.

Introduction

“It should always be kept in mind that expert evidence is merely one tool to be used in proving a case…
The dangers of an over-reliance on expert evidence without considering the significance of the other evidence in the case is a factor that prosecutors need to consider in reviewing any file presented by the police for advice and review”

 

The Duty of an Expert Witness

“The duty of an expert witness is to help the court to achieve the overriding objective by giving opinion which is objective and unbiased, in relation to matters within their expertise. This is a duty that is owed to the court and overrides any obligation to the party from whom the expert is receiving instructions”

Admissibility of Expert Evidence

“Expert opinion evidence is admissible at common law where:
1. It will be of assistance to the court
For expert opinion to be admissible it must be able to provide the court with information which is likely to be outside a judges or a jury’s knowledge and experience, but it must also be evidence which gives the court the help it needs in forming its conclusions.
The role of the expert is to give their opinion based on their analysis of the available evidence. The Bench or jury is not bound by that opinion, but can take it into consideration in determining the facts in issue.
If the expert is seeking to advance an opinion which is not relevant to an issue in the case or which might be deemed a matter of common sense upon which the jury could reach its own conclusions, then the opinion of an expert will be inadmissible.
For instance, in R v Turner (1974) 60 Cr. App R. 80, the issue as to the credibility of a witness was a matter for the jury. Psychiatric evidence as to how an ordinary person who was not suffering from a mental disorder would react to a given situation was held to be inadmissible.
2. The expert has relevant expertise
The individual claiming expertise must have acquired by study or experience sufficient knowledge of the relevant field to render their opinion of value.
The court is concerned that evidence should not be given by experts who are, patently unqualified or little more than enthusiastic amateurs. More commonly, it is vital to ensure that an expert does not give evidence in relation to matters outside of their expertise – see R v Clarke Morabir [2013] EWCA Crim. 162, a case where an expert in fractures and bone disease gave an opinion as to cause of death, in circumstances where the Court of Appeal held that he “did not have the experience or expertise to consider all of the causes of death” in the way that a Home Office registered forensic pathologist would.
However, where the witness possesses relevant formal qualifications in the field of study, challenges to admissibility on the basis of lack of expertise will rarely succeed. Challenges may be more frequent if the expert has gained knowledge based upon experience or informal studies, but, even here, that knowledge can be of assistance to the court.
1. It will be of assistance to the court
For expert opinion to be admissible it must be able to provide the court with information which is likely to be outside a judges or a jury’s knowledge and experience, but it must also be evidence which gives the court the help it needs in forming its conclusions.
The role of the expert is to give their opinion based on their analysis of the available evidence. The Bench or jury is not bound by that opinion, but can take it into consideration in determining the facts in issue.
If the expert is seeking to advance an opinion which is not relevant to an issue in the case or which might be deemed a matter of common sense upon which the jury could reach its own conclusions, then the opinion of an expert will be inadmissible.
For instance, in R v Turner (1974) 60 Cr. App R. 80, the issue as to the credibility of a witness was a matter for the jury. Psychiatric evidence as to how an ordinary person who was not suffering from a mental disorder would react to a given situation was held to be inadmissible.
2. The expert has relevant expertise
The individual claiming expertise must have acquired by study or experience sufficient knowledge of the relevant field to render their opinion of value.
The court is concerned that evidence should not be given by experts who are, patently unqualified or little more than enthusiastic amateurs. More commonly, it is vital to ensure that an expert does not give evidence in relation to matters outside of their expertise – see R v Clarke Morabir [2013] EWCA Crim. 162, a case where an expert in fractures and bone disease gave an opinion as to cause of death, in circumstances where the Court of Appeal held that he “did not have the experience or expertise to consider all of the causes of death” in the way that a Home Office registered forensic pathologist would.
However, where the witness possesses relevant formal qualifications in the field of study, challenges to admissibility on the basis of lack of expertise will rarely succeed. Challenges may be more frequent if the expert has gained knowledge based upon experience or informal studies, but, even here, that knowledge can be of assistance to the court.”

ALSO WORTH READING

There as aspects of the guidance worth reading in general.

  • Case preparation and management
  • Joint reports and conferences between experts
  • Doubts about the competence and credibility of the expert witness
  • Instructing a second expert.
  • Continuing to rely on the discredited expert.
  • Using the expert witness at court.
  • Cross examination.
  • Challenging defence experts.
  • Conflicts of opinion between experts.
  • Expert fees.
  • The model letter of instruction.
  • Specific areas of expertise.
  • The “prosecutors fallacy”.