Book excerpt: This book provides an international legal analysis of the most important questions regarding Iran's nuclear program since 2002. Setting these legal questions in their historical and diplomatic context, this book aims to clarify how the relevant sources of international law - including primarily the 1968 Nuclear Non-proliferation Treaty and IAEA treaty law - should be properly applied in the context of the Iran case. It provides an instructional case study of the application of these sources of international law, the lessons which can be applied to inform both the on-going legal and diplomatic dynamics surrounding the Iran nuclear dispute itself, as well as similar future cases. Some questions raised regard the watershed diplomatic accord reached between Iran and Western states in July, 2015, known as the Joint Comprehensive Program of Action. The answers will be of interests to diplomats and academics, as well as to anyone who is interested in understanding international law's application to this sensitive dispute in international relations.