( i) the liability of the appellant on counts one and three — murder
and attempted murder — was as a principal only; and
( ii) the liability of those charged in counts two and four — man-
slaughter and aggravated assault — was as parties, that is to
say, as aiders, abettors or participants in a common unlawful
Besides, the instructions on the essential elements of second degree
murder and attempted murder were limited to the appellant as
principal and contained not a whisper of any other mode of
 In addition to the trial judge’s instructions, the respondent
continues, the decision trees provided to the jury as deliberation
aids confirmed that the appellant’s liability for murder and
attempted murder was to be assessed as principal, not as a party.
And for the co-accused on counts two and four, as parties, not as
 The respondent accepts that the trial Crown misstated
the mental element in murder in his closing address to the jury. But the trial Crown told the jury, as did the trial judge, that
the jury was to take its instructions on the law from the judge,
not from counsel. And the trial judge accurately described the
mental element in murder under s. 229(a) despite the inclusion of a statement that reflected error.
The governing principles
 The principles that govern our decision on this ground of
appeal are not controversial. Some have to do with the standard
we are to apply when reviewing jury instructions for errors.
Others are concerned with instruction content, in other words,
the substance of what must be said about the mental element in
murder as defined in s. 229(a), and the modes of participation
contained in s. 21 of the Criminal Code.
 The entitlement of the parties in a criminal trial is that the
jury be properly instructed. Perfection is not the standard against
which we test jury instructions: R. v. Jacquard,  1 S.C.R.
314,  S.C.J. No. 21, at para. 2.
 Our review involves a functional approach. We test the instructions to determine whether, taken as a whole, they properly
equipped the decision-maker to render a true verdict on the evidence adduced and the positions advanced at trial: R. v. Calnen,
 S.C.J. No. 6, 2019 SCC 6, 430 D.L.R. (4th) 471, at para. 8;
R. v. Bailey,  O.J. No. 3508, 2016 ONCA 516, 339 C.C.C.
(3d) 463, at para. 42. We also must bear in mind that a jury
charge does not take place in splendid isolation, but rather in the