Is international law (IL) a substitute for armed force in international relations? Put differently, can IL be state A's means of getting state B to do its bidding against B's will? Ideally, that is exactly what law is: a means of coercion that preempts the use of force. In the face of competing claims, divergent perceptions, or conflicting interests, law tells us who or which side is in the right, saving us the trouble of a physical confrontation. Of course, we rely on law to be effective in this task because it is typically backed by a threat of enforcement. Those who break a law tend to incur a penalty. In the archetypal understanding of enforcement that penalty is force or violence. Law is hence at best a temporary substitute for force. When push comes to shove the coercive power of law depends on violence.To the extent that this is still the dominant way in which we think about law, international lawyers have to engage in what Thomas Franck aptly called "defensive ontology" (Franck 1995, 6). If association with the coercive power of the state is what renders a rule a law, then IL cannot really be law. After all, international relations are anarchical in the sense that states are not subject to a superior authority with a monopoly on the use of force that could enforce this "law." States comply with it either because that is how they want to behave anyway or because a rule of IL is backed by the material power of another state (for this view see Goldsmith and Posner 2005; Grieco 1988; Krasner 1999; Nardin 2008; Thompson 2012). As enforcement accounts for the coercive power of law, the answer to the initial questioncan IL be a substitute for armed force in international relationsmust be no. It cannot even be relied on to be the temporary substitute that domestic law is. As Eric Posner puts it: "[l] aws do not enforce themselves. If a weak country cannot coerce a more powerful country through force of arms, then it cannot coerce the other country with law either" (Posner 2011).