Opinion Evidence

INTRODUCTION

This fact sheet describes the law of evidence as it relates to the admissibility or otherwise of a witness’s opinion in criminal cases.

THE GENERAL RULE

The general rule is that the opinions of witnesses are not admissible. Witnesses are normally confined to stating the facts. The reasoning behind this rule is that it is the role of the court to form any opinions which need to be formed, and there is a risk that the court may be unduly influenced by the opinion of a witness who may not be as impartial as the court, and the court must draw its own inferences from the facts stated.

EXCEPTIONS TO THE GENERAL RULE

There are two important exceptions to the general rule. These occur in cases where the court lacks the witness’s competence to form an opinion on a particular issue whether through lack of direct knowledge or through lack of expertise.

EYE WITNESS’ OPINIONS OR OPINIONS AS SHORTHAND FOR FACTS

Statements of opinion by an eye witness to the facts in issue are often a convenient way of stating several facts, e.g., “Bob was drunk”. These types of statements will generally be admissible as long as a proper appraisal of the facts does not call for any special expertise.

Other examples of opinion statements that are usually admissible include statements about the speed of a car involved in an accident, and the identification of persons, animals, places or things (which are technically opinion statements).

EXPERT OPINIONS

Where the court is asked to determine issues that are so far removed from the court’s experience, expert opinion on those issues is admissible. (Folkes v Chadd)

The areas in which expert evidence is admissible will usually be those in the medical field, e.g., a pathologist’s opinion as to the cause of death, or in the scientific field, e.g., the interpretation of data collected using a sound level meter with a frequency analysis etc. However, there is often a fine line between those issues that do call for expert’s opinion, and those that do not.

Psychiatric evidence is particularly fraught with difficulties in that the courts have decided that this area often deals with matters of human nature and behaviour within the limits of normality, which is something that the court can determine itself without expert psychiatric evidence. (R v Turner)

WHO IS AN EXPERT?

If an issue requires the opinion evidence of an expert, only a suitably qualified expert can give it.

The starting point in examining in chief an expert witness is to establish his/her expertise. This does not necessarily mean that s/he has to have formal qualifications. However, it will not be easy to satisfy a judge that a witness is an expert in a field if s/he lacks formal qualifications. (R v Silverlock)

NATURE AND CONTENT OF EXPERT EVIDENCE

An expert’s opinion will be based on much more than the facts of the case being considered in court. It will be based on experience and information obtained from textbooks etc. This information is technically hearsay, but is admissible as helping to form the expert’s opinion. (R v Abadom)

It should be noted that the facts of the case in which the expert’s opinion is sought must be proved by admissible evidence, which may be given by the expert, or some other witness, e.g., a scientist may have carried out routine tests, which are then interpreted by an “expert”. The scientist must give evidence of the tests and the results recorded, whilst expert opinion evidence is then given about the interpretation of those results.

ADVANCE NOTICE OF EXPERT EVIDENCE

In general, the prosecution is obliged to disclose expert evidence, along with evidence of facts to the defence, for the purposes of natural justice. There is generally no reciprocal duty on the defence for summary cases.

For Crown Court cases, however, the position was changed by the Crown Court (Advance Notice of Expert Evidence) Rules 1987, made under the Police and Criminal Evidence Act 1984 (PACE) S. 81. Under these rules, any party proposing to rely on expert evidence is required to furnish the other side with a written statement of that expert’s findings and/or opinion. The other side may further request written details of any test or calculation etc. relied on by the expert in giving his/her opinion. If these rules are not adhered to, the side wishing to rely on the opinion must seek the court’s leave to admit it.

The expert report may be relied on in court even if the maker is not to give oral evidence by virtue of S.30 of the Criminal Justice Act 1988, but only where, the court gives leave to do so. In considering whether to permit such a report, the court will consider the relevance of the report’s contents, the reason why the maker cannot give oral evidence, and the unfairness caused to the accused in admitting it etc.

The Criminal Procedure and Investigations Act 1996 S.20 allows for similar rules of court to be made for summary cases (in the Magistrates Court).

RESPONSIBILITIES OF EXPERTS

Some recent cases have set out some of the responsibilities of expert witnesses and the Courts have admonished those that approach their task in a less than prepared manner.

In Autospin (Oil Seals) Ltd v Beehive Spinning (a firm) the court stated that an expert witness carries out a lot of responsibility because their evidence is afforded special respect and weight, particularly by a jury. An expert must approach the case in which s/he is giving their opinion seriously, and expect to be strongly censured if s/he doesn’t. This necessarily involves researching the case thoroughly so that it is a considered expert opinion.

The case of National Justice Compania Noviera v Prudential Assurance added that a well as giving independent and unbiased evidence, an expert should tell the court if s/he did not have experience of a certain area being questioned on, or that s/he had insufficient information on which to base a properly researched conclusion.

REFERENCES

Autospin (Oil Seals) Ltd v Beehive Spinning (a firm) 1995.

Criminal Justice Act 1988.

Criminal Procedure and Investigations Act 1996.

Crown Court (Advance Notice of Expert Evidence) Rules 1987.

Folkes v Chadd (1782) 3 Doug KB 157.

National Justice Compania Noviera v Prudential Assurance.

Police and Criminal Evidence Act 1984.

R v Abadom (1983) 76 Cr App R 48.

R v Silverlock (1894) 2 QB 766.

R v Turner (1975) QB 834 CA

Back

Forward to Privilege

Forensicmed.co.uk book store T-shirt store

This site aims to provide educational resources for medical students in the fields of forensic pathology, clinical forensic medicine, forensic psychiatry and forensic science. All illustrations used are believed to be in the public domain, and royalty free. However, if this is not the case, and you are the copyright holder, I apologise, and will remove the relevant illustrations if required.