In R. v. Lacasse, 2015 SCC 64,  3 S.C.R. 1089 the accused was charged with impaired operation of motor vehicle causing death. It was undisputed on appeal that at the time of the motor vehicle accident, the accused was impaired by alcohol.
The majority of the Supreme Court of Canada noted in obiter that although the consumption of cannabis by the accused may not have played a role in fatal motor vehicle accident, it could be considered an aggravating factor on sentence, as it was evidence of the accused’s irresponsibility. Presumably because of the risk the accused undertook when he consumed cannabis and then drove.
R. v.Lacasse, 2015 SCC 64,  3 S.C.R. 1089at para 84