could be generated by the situation described by Mr. Suarez-Noa
immediately before the homicide. The jury did not need
Dr. Gojer to tell them about the potential volatility of a situation
like that described by Mr. Suarez-Noa. Nor could Dr. Gojer assist
the jury in the crucial task of assessing the credibility of
Mr. Suarez-Noa’s description of those events.
 Expert opinion evidence, like that given by Dr. Gojer in
this case, has been rejected in several cases as an unnecessary
intrusion upon the jury’s responsibilities: see, e.g., R. v. Lovie
(1995), 24 O.R. (3d) 836,  O.J. No. 2065, 100 C.C.C. (3d) 68
(C.A.), at pp. 76-78 C.C.C.; R. v. Currie,  O.J. No. 2191,
166 C.C.C. (3d) 190 (C.A.), at paras. 66-67; R. v. Rogers, 
B.C.J. No. 1580, 198 C.C.C. (3d) 449 (C.A.), at para. 79; and
R. v. Liard,  O.J. No. 4000, 2013 ONSC 5457 (S.C.J.),
at paras. 363-77.3
 The observations of the trial judge in Liard, at para. 377,
a case in which the defence offered evidence from Dr. Gojer, not
unlike the evidence offered here, are apposite:
Dr. Gojer’s anticipated evidence is not admissible because it is not neces-
sary to assist the jury. Rather, it is a summary of conclusions about
Mr. Lasota’s [the accused] reactions to stresses and difficulties in his life.
The jury is able to assess these circumstances without Dr. Gojer’s evi-
dence . . . It [Dr. Gojer’s evidence] tends to dress up matters of common
experience in the cloak of expertise, giving rise to a fear that the jury would
give undue weight to the opinion.
 Ms. Pringle, counsel for Mr. Suarez-Noa, persuasively
argued that even if Dr. Gojer’s opinion concerning Mr. Suarez-Noa’s mental state was inadmissible, the Crown made a tactical
decision, after advancing a very limited objection to his evidence,
to make its case by cross-examining Dr. Gojer. She stresses that
the Crown did not object to any part of Dr. Gojer’s evidence
when he was testifying. Ms. Pringle argues that the Crown, having made a tactical choice to advance its case through the cross-examination of Dr. Gojer, should not be allowed to argue on
appeal that none of his evidence was admissible.
 I was initially attracted to this submission. However, on
further reflection and a more thorough review of the trial record,
I cannot accept the argument.
3 Counsel for the respondent refers to R. v. Gillett,  O.J. No. 2337,
159 O.A.C. 247 (C.A.), in support of the admissibility of Dr. Gojer’s evidence. In its brief endorsement, the court referred to the evidence given
by Dr. Gojer. That evidence was similar to evidence he gave in this
case. From the endorsement, it would not appear that the admissibility of
Dr. Gojer’s evidence was in issue on the appeal.