Do Human Rights Treaties Make a Difference?

International lawyers for the most part assume that, as Louis Henkin memorably put it, "almost all nations observe almost all principles of international law and almost all of their obligations almost all of the time."'This assumption undergirds the work of many legal scholars and practitioners, who endeavor to explicate and form the law presumably because they believe that it has real impact.Indeed, the claim that international law matters was until recently so widely accepted among international lawyers that there have been relatively few efforts to examine its accuracy. 2Yet this view long coexisted with a much more skeptical conception of international law among international relations scholars-a conception that holds that, in the immortal words of Thucydides, "[t]he 1. Louis