(c) The trial judge’s rulings
 The trial judge provided a detailed oral ruling on the
admissibility of Dr. Smith’s expert evidence, and a second oral
ruling permitting his reports to be filed in evidence.
 After noting that the gatekeeper function is particularly
important when the jury is the fact-finder, the trial judge
adverted to the potential for distorting the fact-finding process
where an expert provides oath-helping evidence.
 She concluded [at para. 7] that Dr. Smith’s credentials and
experience qualified him as an expert and that expertise as
a mental health clinician was necessary, as “[w]hether the plaintiff
has suffered psychological and/or emotional harm is a central issue
in this civil action for damages for alleged sexual abuse”. She
stated that Dr. Smith’s proposed evidence was “relevant to that
issue and to the nature and extent of that harm if any, as that is
a factor to be considered by the jury in assessing damages”.
 The trial judge concluded that the probative value of the
proposed evidence outweighed its prejudicial effect. She acknowledged that the oath-helping concern was genuine, and would
be addressed with a mid-trial jury instruction and in her final
 The trial judge also noted that, as a treating clinician,
Dr. Smith was a participant expert, whose evidence could be
accepted without compliance with rule 53.03 of the Rules of Civil
Procedure. She quoted the limitation on such evidence articulated
in Westerhof: that the opinion to be given be “based on the witness’s observation of or participation in the events at issue” and
that “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”:
Westerhof, at para. 60.
 As a result, the trial judge permitted Dr. Smith to testify
about “his observations of, impressions formed regarding and
treatment provided to the plaintiff as set out in the reports prepared by him”. She ruled that he was not to give opinion evidence
as to any other matter, including (1) whether Mr. Imeson would
ever get out of prison; (2) whether he fit the characteristics of
someone who had been sexually abused; and (3) whether he
matched the characteristics that predatory sex offenders seek out.
The exception was that Dr. Smith was permitted to give an opinion about the therapy he would have recommended had Mr. Imeson not terminated treatment. The trial judge cautioned counsel
to exercise appropriate caution in their questioning of Dr. Smith
to abide by her ruling.