What is the Role of an Expert in Tax Cases?

The role of an expert in tax cases is to assist the court by providing specialized knowledge, analysis, and opinion evidence on technical or complex matters that are outside the ordinary experience of the judge.

The expert’s primary duty is to the court, not to the party who retained them. This duty requires the expert to be impartial, objective, and not act as an advocate for any party. This is contrary to the thinking of many litigants, who believe that the expert is hired to to be their representative.

Key Duties of Experts in Tax Cases

1. Assisting the Court, Not Advocating for a Party
The main role of an expert witness is to assist the court in assessing evidence on scientific, technical, or specialized matters. The expert’s overriding duty is to the court, and this duty overrides any obligation to the party retaining the expert. The expert must be independent and objective and must not be an advocate for a party.

2. Impartiality and Objectivity
The expert must provide opinion evidence that is fair, objective, and non-partisan. The expert’s evidence should be related only to matters within their area of expertise.

3. Qualification and Admissibility
The court must be satisfied that the expert is properly qualified in the relevant field. The admissibility of expert evidence is governed by the criteria set out in R. v. Mohan, which requires that the evidence be relevant, necessary to assist the trier of fact, not subject to any exclusionary rule, and provided by a properly qualified expert.