This case was a major ruling on duress and Lamer C.J. determined the meaning of “purpose” in s. 21(1)(b): Every one is a party to an offence who does or omits to do anything for the purpose of aiding any person to commit it
The interpretation that equates purpose with intention (as opposed to desire) best reflects the legislative intent underlying the subsection.
R. v. Buzzanga and Durocher  49 C.C.C. (2d) 369 (Ont. C.A.)
The defendants put out a satirical document that appeared to be promoting hatred of French Canadians. They actually intended the document to sway public opinion in favour of building a French-language high school in the area. They were charged and convicted with wilfully promoting hatred. The trial judge treated the defendants’ testimony that they wished to create a “controversy, furor, and uproar” as a virtual admission that they had the state of mind requisite for guilt.
Did the trial judge err in his decision?
Yes. Appeal allowed; new trial ordered.
An intention to create “controversy, furor and uproar” is not the same thing as an intention to promote hatred and it was an error to equate them.
R. v. Chapin  2 S.C.R. 121 (Please ignore this)
R. v. Docherty  72 C.R. (3d) 1 (S.C.C.)
Docherty was caught sitting in a car drunk and he pleaded guilty to a charge of having care and control of a motor vehicle with excessive alcohol in his blood. This constituted Docherty’s failure to comply with the terms of a previous probation order to keep the peace and be of good behaviour. He did not think he was doing anything wrong and he thought the car would not start. The trial judge believed him on these points.
Can an accused be convicted of a summary offence of breaching a probation order without mens rea?
An accused cannot have wilfully breached his probation order through the commission of a criminal offence unless he knew that what he did constituted a criminal offence. Where knowledge is itself a component of the requisite mens rea, the absence of knowledge provides a good defence.
R. v. Théroux  2 S.C.R. 5