reports, on the questions of liability (whether the sexual assaults
occurred), causation (whether he suffered harm as a result), as
well as damages. She also proposed that Dr. Smith would offer
opinions on four matters extending beyond what was contained in
his reports, including whether Mr. Imeson had the characteristics
and behaviour of a sexual assault victim.
 Mr. Imeson’s counsel sought to file Dr. Smith’s complete
reports in evidence, and to have him testify. Alternatively, she
proposed to file as business records, under s. 35 of the Evidence
Act, R.S.O. 1990, c. E.23, the reports with all of Dr. Smith’s opinions redacted. For this purpose, she provided the trial judge with
a copy of the reports, highlighting the opinions.
 Defence counsel opposed the admission of Dr. Smith’s
opinion evidence on a number of grounds.
 They asserted that Dr. Smith’s opinions went beyond those
of a participant expert.
 They also argued that Dr. Smith’s evidence did not meet
the Mohan criteria: he lacked the necessary training and expertise to provide an opinion on childhood sexual abuse and his evidence was not necessary or relevant, especially on the issues of
causation and liability. They submitted that the prejudicial effect
of the evidence, including its oath-helping potential, outweighed
its probative value, such that Dr. Smith should not be permitted
to testify at all.
 Defence counsel also took particular issue with the admission into evidence of Dr. Smith’s reports. They argued that, as
a general rule, parties cannot both file a medical report and call
the practitioner as a witness. Moreover, in this particular case,
the reports caused irreparable prejudice to the defendants given
their oath-helping nature.
 Dr. Smith testified in the voir dire. He explained his qualifications and experience — that he had been a mental health clinician, working in the prison system for 18 years. He described
his areas of specialty as (1) preparing assessments of risk to
reoffend for parole board hearings, (2) providing crisis response
for inmates engaging in suicidal or self-harming behaviours and
(3) providing counselling for inmates with trauma. He confirmed
that he had conducted no research in the field of childhood sexual
trauma and abuse.
 Dr. Smith acknowledged that his role was not to determine
whether what Mr. Imeson told him about being abused had
occurred in fact, and that in his therapeutic role he was willing to
accept that what Mr. Imeson told him was the truth.