This volume features a selection of the best scholarship on international law as it is relevant to the proliferation of weapons of mass destruction. The essays consider the nonproliferation legal regime as a normative system and offer a more discrete consideration of international law in each weapons of mass destruction technology area: nuclear weapons proliferation; chemical and biological weapons proliferation; and delivery systems proliferation. In addition, the essays consider the closely related questions of the role, authority and track record of the UN Security Council in monitoring, implementing and enforcing compliance with these primary sources of nonproliferation law.