An expert witness is a person who, by virtue of education, training, skill, or experience, is believed to have specialized knowledge in a particular subject beyond that of the average person. The primary duty of an expert witness is not to the party who hired them but to the court. Their role is to provide impartial and objective opinions on matters within their expertise to assist the court in understanding the evidence or determining a fact in issue. This duty to provide unbiased assistance to the court overrides any obligation to the person from whom they receive instructions or payment.

A. The role of an expert witness is to be impartial and assist the court, not to act as an advocate or "hired gun" to defend a client.

B. This definition is too narrow. Expert witnesses can come from any field, not just engineering or geoscience, and their role is to provide opinion, not just confirm/disprove testimony.

C. Determining legal culpability is the ultimate function of the judge or jury; the expert's opinion is evidence to assist them in making that determination.

1. Marston, D. L. (2018). Law for Professional Engineers: Canadian and Global Insights (5th ed.). McGraw-Hill Ryerson. Chapter 6, pp. 100-101.

2. Samuels, B. M., & Sanders, D. R. (2015). Practical Law of Architecture, Engineering, and Geoscience (3rd Canadian ed.). Pearson Canada. Chapter 23, p. 338.

3. Andrews, G. C. (2019). Canadian Professional Engineering and Geoscience: Practice and Ethics (6th ed.). Nelson. Chapter 4, p. 91.