The Supreme Court’s judgment in Jogee and Ruddock v The Queen1 substantially altered the criminal law’s approach to secondary liability. However, the judgment left numer- ous important issues unresolved. In particular, the circum- stances in which a secondary party is excused liability on the basis of an overwhelming supervening act (“OSA”) of the principal remains unclear. The Court of Appeal recently discussed OSA in Lanning and Camille,2 but it too left im- portant questions unanswered. In this article we examine this concept, which is being encountered with increasing frequency in practice.