This paper offers a critical reconsideration of the traditional doctrine that responsibility for a crime requires a voluntary act. I defend three general propositions: first, that orthodox Anglo-American criminal theory (as represented by Michael Moore's updating of Austin's volitionalism) fails to adequately explain why criminal responsibility requires an act. Second, when it comes to the just definition of crimes, the act requirement is at best a rough generalization, rather than a substantive limiting principle. Third, that the intuition underlying the so-called "act requirement" is better explained by what I call the "practical agency condition," according to which punishment in a specific instance is unjust unless the crime charged was...