The Iran–US. Claims Tribunal, concerned principally with the claims of US nationals against Iran, is the most important international claims tribunal to have sat in over half a century. Its jurisprudence is bound to make a uniquely important contribution to international law and, in particular, the law relating to aliens, treaty law, and international arbitral procedure. The 40th volume of the Iran–US Claims Tribunal Reports makes available to the public the Tribunal's most recent work, including an important award in a large dispute between Iran and the United States. This volume of the Reports is a critical contribution to the field of international arbitration that will inform and guide the practice of international arbitration practitioners from around the world.