Mr. Imeson’s mental health status at the time of his assessments
and the appropriate course of treatment.
 The respondent, for his part, submits that the trial judge
properly identified Dr. Smith as a participant expert and properly
set limits on his testimony in her ruling.
 As explained above, in her oral ruling on the voir dire, the
trial judge recognized the limited role of a participant expert
under Westerhof. She ruled that Dr. Smith was permitted to testify
about [at para. 15] “his observations of, impressions formed
regarding and treatment provided to the Plaintiff as set out in the
reports prepared by him . . . without having to comply with Rule
53.03” but not anything beyond the reports (other than what ther-
apy he would have recommended for Mr. Imeson). She also allowed
the reports to be tendered into evidence.
 As the trial judge recognized, great care was required to
ensure that Dr. Smith did not provide any opinion evidence that
exceeded the scope of proper opinions to be offered by a participant
expert. Unfortunately, she permitted that to happen by admitting
Dr. Smith’s unredacted reports into evidence and permitting him
to testify about anything that was contained in the reports.
 In considering the proper scope of Dr. Smith’s evidence as
a participant expert, it is important to remember how participant
experts differ from litigation experts.
 In the civil litigation context, a litigation expert is subject to
rule 53.03. This rule requires, among other things, an expert report
that sets out the expert’s opinions, as well as an acknowledgment of
the expert’s duty. Typically, an expert report provides a “roadmap of
the anticipated testimony and specific limits may be placed on certain areas of testimony”: Bruff-Murphy (Litigation guardian of) v.
Gunawardena (2017), 138 O.R. (3d) 584,  O.J. No. 3161, 2017
ONCA 502, at para. 62, leave to appeal to S.C.C. refused 
S.C.C.A. No. 343. The expert’s report will provide the framework for
discussion about the proper scope of the expert’s testimony.
 In contrast, under Westerhof, participant experts may give
opinion evidence without complying with rule 53.03. Typically,
any opinions that are sought to be introduced are found in the
clinician’s clinical notes and records, or in reports prepared for
the purpose of consultation and treatment.
 In Westerhof, this court explained the proper role of a par-
ticipant witness, at para. 60, as follows:
[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 evi-
dence for the truth of its contents without complying with rule 53.03 where: