This comment criticizes the majority opinion in the judgment delivered by the Quebec Court of Appeal in Rochon v. The Queen. Contrary to the approach of the Court of Appeal, the author of this comment argues that despite the absence of a legal duty, the omission to do something may constitute a source of criminal liability for an aider or an abettor. What is necessary is that the aider or abettor refrains from acting so that he can influence the course of the offence. Similarly, unlike the concurring opinion of Justice Kasirer, the author of this comment holds that in order to bear criminal liability, the aider or abettor does not need to desire the consequences of the offence. It is sufficient for him to know that the principal offender is committing the offence or is about to commit it, and to knowingly provide him with the material or moral support.