This article uses history to explore how prominent international lawyers explain seemingly transgressive state behavior. It begins with the Russian annexation of Crimea in 2014. This seizure of another state’s territory by force of arms seems to violate everything that the UN Charter and the post-1991 settlement of the Cold War stood for. Surprisingly, the various steps employed by the Russians to give their actions a veneer of legality follow almost exactly the playbook used by the United States in 1903 to seize the Panama Canal Zone. In both instances, leading professors of international law ‒ Rein Müllerson, the Anglo-Estonian scholar, publicist, and stateman in the case of Crimea, John Bassett Moore, the most prominent U.S. international lawyer of the day, in the case of Panama ‒ sought to justify these acts in the face of what they both acknowledged was a general ban on wars of conquest. The details of these transgressions and the justifications offered by their prominent defenders shed light on the work that international law does. These events provide an opportunity to use the tools of comparative international law to uncover and assess claims about the validity of otherwise repugnant state behavior. This emerging field downplays the judgmental, project-oriented focus of contemporary international law in favor of striving for a better understanding of systematic differences in the way significant actors use international law. In a world riven with entrenched and unbridgeable differences, counting on states to agree to an extensive body of deep rules to govern their international behavior is utopian, but expecting them to understand their adversaries’ perceptions of their international interests and the ways they will explain themselves is not. The bipolar world of the Cold War required a tradeoff between consensus and comprehension. The contemporary multipolar world, with its challenges and conflicts, may do the same.