limited to proving the respondent’s culpability by establishing
that he was the “getaway driver”.
B: On what legal basis could the respondent be found to be
a party to the offence of manslaughter?
 In its argument on the directed verdict application, the
trial Crown relied on s. 21(1)(b) of the Criminal Code, R.S.C.
1985, c. C-46, the aiding provision, and s. 21(2), the common
purpose section. The trial judge held that as the Crown was
restricted to arguing that the respondent was the getaway
driver, it followed that the respondent could only be liable as
an aider under s. 21(1)(b).
 With respect, even if the trial judge was right in restricting the Crown to the argument that the respondent was the getaway driver, his potential liability for manslaughter still flowed
exclusively from s. 21(2) of the Criminal Code.
 As my colleague, Watt J.A., has explained with admirable
clarity in R. v. Simon (2010), 104 O.R. (3d) 340,  O.J. No.
4723, 2010 ONCA 754, at paras. 39-43, s. 21(1) refers to parties
who participate in the offence charged as perpetrators, aiders or
abettors. To aid in the commission of an offence, an accused must
do something “for the purpose” of aiding another in the commission of that offence. Liability under s. 21(2) rests on an entirely
different basis. Section 21(2) imposes party liability for offences
that are incidental to the carrying out of a common unlawful
design. Liability under s. 21(2) requires the Crown to prove that
an accused formed an intention with others to engage in an
unlawful purpose and that one or more of the others, in carrying
out that unlawful purpose, committed a different offence that the
accused knew or ought to have known was a probable consequence of carrying out the common unlawful purpose.
 On the Crown’s case, the respondent was an aider in the
robbery and a party to the common unlawful purpose of committing a robbery. There was no evidence that he did anything for
the purpose of aiding the robbers in harming any of the victims
of the robbery. The respondent’s role in planning or executing
the robbery could not make him an aider in the homicide that
occurred during the robbery.
 I think this was quintessentially a case for the application
of s. 21(2). The respondent, having allegedly agreed to the commission of one crime, the robbery, was alleged by the Crown to
be responsible for the commission of a second crime committed
by one of the parties to the robbery in the course of carrying out
the common unlawful purpose. Section 21(2) addresses exactly
that kind of criminal culpability.