Expert opinions and evidence
Evidence at a hearing may be given by witnesses (whether orally or in writing such as in an affidavit, witness statement or expert report) or in documentary form (whether documents, plans, maps or photographs). The evidence given may be of facts or opinions by experts. These pages provide information on experts giving expert evidence.
The general rule against opinions and the exception for expert opinions
The rules of evidence distinguish between evidence of facts and evidence of opinion. The general rule is that witnesses should only give evidence of fact, not opinion. Evidence of fact involves direct observation of facts using the five senses, such as what people saw or heard. Opinion evidence is an inference or conclusion drawn from facts. The general rule is that it is the function of the Court to draw inferences or conclusions from the facts proven by witnesses of fact.
There is, however, an exception to the general rule for opinion evidence given by experts. Where matters involve specialised knowledge, the Court may not have that specialised knowledge so as to be able to draw the proper inferences from the facts stated by the witnesses of fact. The Court needs the assistance of a person with the specialised knowledge to be able to draw the proper inferences.