What is an expert witness?
An expert witness is an independent expert who gives or prepares evidence in Court proceedings on matters within their expertise. An expert witness needs experience but not necessarily qualifications in their area of expertise to give expert evidence. In England and Wales, expert witnesses are the only kind of witnesses who are allowed to give both evidence of fact and evidence of opinion.
The expert evidence will normally take the form of a written report which can be presented to a judge, and in rare cases involves an appearance in Court for cross-examination.
An expert witness’s duty is strictly defined by the Civil Procedure Rules Part 35 and the accompanying Practice Direction 35. In particular, an expert witness’s duty is to the Court rather than to either party in the proceedings. So an expert witness is not a ‘hired gun’ in favour of one side or the other. Expert witnesses are approved or appointed by the Court.
Experts – overriding duty to the court
(1) It is the duty of experts to help the court on matters within their expertise.
(2) This duty overrides any obligation to the person from whom experts have received instructions or by whom they are paid.
Civil Procedure Rules 35.3
Single joint expert
Where both parties to proceedings wish to appoint an expert, the Court may appoint a single joint expert (SJE) as opposed to two opposing experts. The single joint expert then prepares a single report and corresponds with solicitors of both parties, and may be cross-examined by advocates for both parties in Court.
Expert witness vs expert advisor?
At Fast Data Science we offer both expert advisor and expert witness services in machine learning and data science. What is the difference between an expert advisor and an expert witness?
An expert advisor can be hired informally to write an expert report or give advice to a party in litigation. However, an expert witness can only be instructed by a solicitor once civil proceedings have been issued and a court has approved the use of an expert witness. Parties to proceedings must declare the use of any expert witnesses and the costs incurred to the Court. These rules avoid ‘expert shopping’, i.e. instructing multiple experts until a report favourable to a party’s case is received.
The report written by an expert advisor may take any format, such as a simple letter. However, an expert witness’s report must be compliant with the Civil Procedure Rules Part 35, and Practice Direction 35.
Should you require either an expert advisor or expert witness in machine learning, please contact us and we will be glad to assist.