Expert Witnesses vs Lay Witnesses

There are some key differences between expert witnesses and witnesses of fact. The evidence that these witnesses provide to the court (or tribunal) is different. They will also be cross examined in different ways. As such, there are different ways in which these witnesses should prepare.

Expert Witness

The role of an expert witness is to provide an opinion to the Court. Expert witnesses provide the Court (or Tribunal) with evidence on which it has no first-hand knowledge. Typically experts are specialists within a specific field, for example: accountants, doctors or engineers. This opinion will typically be first provided to the Court in a written report (or reports). Other parties will often have their own expert witness (or expert witnesses) to provide expert evidence, and these experts will also provide their initial evidence to the Court by way of an expert report. Often the expert witness’ evidence and report is tested in the Court under cross examination. The testimony provided by expert witnesses in Court under cross examination can be determinative of the evidence on that point, and indeed the proceedings generally.

Factual (Lay) Witness

Factual witnesses (also known as lay witnesses) also provide evidence to the court. However, unlike expert witnesses (above), witnesses of fact provide the court with direct evidence of facts as the witness perceived them – for example, what the witness saw and what the witness heard. Factual witnesses (cf. expert witnesses) are not to provide opinions to the Court. Often witness evidence is provided to the court initially by way of a written affidavit or witness statement. Other witnesses (including for any opposing parties) will also provide their statements. Again, this evidence is also tested in the court by the giving of oral evidence under cross examination. Such testimony can be crucial in the Court’s (or tribunal’s or inquiry’s) decision in the matter.

Obligations of witnesses

Expert and factual witnesses are both obliged to tell the truth to the Court: “the truth, the whole truth and nothing but the truth”. A failure to do this can be a criminal offence, and it will mean a loss of credibility for the witness (and potentially professional disciplinary proceedings for any expert witnesses).

Expert witnesses have additional duties to assist the Court in the provision of their evidence, rather than to the parties themselves.

Effective witness evidence

Loquitur’s witness familiarisation training courses are specifically designed for both expert witnesses and witnesses of fact to effectively deliver their testimony to the Court while under cross examination.

Some tips and suggestions for all witnesses likely to undergo cross examination can be found here.

Some specific suggestions for expert witnesses in Court are available here.

To see how we can help you please contact us.

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