“As I have said, I do not agree with the Divisional Court’s conclusion that the type of evidence – whether fact or opinion – is the key factor in determining to whom rule 53.03 applies.
Instead, I conclude that a witness with special skill, knowledge, training, or experience who has not been engaged by or on behalf of a party to the litigation may give opinion evidence for the truth of its contents without complying with rule 53.03 where:
-
-
- the opinion to be given is based on the witness’s observation of or participation in the events at issue; and
- the witness formed the opinion to be given as part of the ordinary exercise of his or her skill, knowledge, training and experience while observing or participating in such events.
-
Such witnesses have sometimes been referred to as “fact witnesses” because their evidence is derived from their observations of or involvement in the underlying facts. Yet, describing such witnesses as “fact witness” risks confusion because the term “fact witness” does not make clear whether the witness’s evidence must relate solely to their observations of the underlying facts or whether they may give opinion evidence admissible for its truth. I have therefore referred to such witnesses as “participant experts”.
Similarly, I conclude that rule 53.03 does not apply to the opinion evidence of a non-party expert where the non-party expert has formed a relevant opinion based on personal observations or examinations relating to the subject matter of the litigation for a purpose other than the litigation.
If participant experts or non-party experts also proffer opinion evidence extending beyond the limits I have described, they must comply with rule 53.03 with respect to the portion of their opinions extending beyond those limits.
As with all evidence, and especially all opinion evidence, the court retains its gatekeeper function in relation to opinion evidence from participant experts and non-party experts. In exercising that function, a court could, if the evidence did not meet the test for admissibility, exclude all or part of the opinion evidence of a participant expert or non-party expert or rule that all or part of such evidence is not admissible for the truth of its contents. The court could also require that the participant expert or non-party expert comply with rule 53.03 if the participant or non-party expert’s opinion went beyond the scope of an opinion formed in the course of treatment or observation for purposes other than the litigation.”