Abstract
In addition to requiring subjective culpability, criminal offenses typically involve two objective features: action and harm. In the paradigmatic case, both features are present, but criminal law also allows for liability where either of them is absent. Rules governing omission liability enable punishment where the offender performs no act, while rules defining inchoate crimes (such as attempt) impose liability where the offender causes no harm. In different ways, these two sets of rules establish the minimum threshold of objective conduct-to use the classic term, the minimum actus reus-required for criminal liability. The absolute floor for a criminal actus reus, then, would be defined by the intersection of these two sets of rules. The prospect of liability for inchoate omissions, involving no act and no harm, exists at the frontier of the state's authority to criminalize conduct and, whether allowed or rejected, effectively determines the outer boundaries of that authority. Accordingly, inchoate-omission liability raises fundamental issues about the nature and proper scope of criminal law. This article considers those issues, asking whether criminal punishment for harmless inaction is legally possible, empirically observable, or normatively desirable and, perhaps surprisingly, answering all three of these questions in the affirmative. However unlikely or dubious the legal math may seem, it turns out that zero action plus zero harm can, does, and should sometimes add up to a crime.