What is the test for co-principal liability in a murder case?

There was no evidence of any other “significant contributing cause” to the deaths of the victims other than the gunshot wounds. There was no basis on the evidence admitted at trial to infer that two persons, acting together, caused the deaths of the victims in any of the six counts such that they would be rendered co-principals; there could only have been one shooter of the gunshot which caused the victims’ deaths. I agree with the appellant that the potential for a situation such as in Miller v. The Queen, 1976 CanLII 12 (SCC), [1977] 2 S.C.R. 680, simply did not exist here. There was no evidence that there may have been one person holding the gun, and one person who pulled the trigger, and thus two participants in the unlawful act causing death. Potential liability for other forms of participation in those murders had to flow, not through co-principal liability, but through aiding and abetting.