The legalization of world politics is often celebrated for reducing impunity for those who contribute to humanitarian crises. This may sometimes be true but the opposite is also true. In 2010, United Nations peacekeepers unwittingly brought cholera to Haiti and sparked an epidemic. Nearly a million people were made sick and 8,500 died. Legal activists have sought to hold the UN responsible for the harms it caused and win compensation for the cholera victims. However, these efforts have been stymied by the structures of public international law—particularly UN immunity—which effectively insulate the organization from accountability. In short, the UN is empowered, and the cholera victims disempowered, by legalization. The Haiti case powerfully illustrates the dangers of legalism, which have been largely overlooked in discussions of international law, and suggests that law alone is an inadequate arbiter of responsibility in international politics.