The Arms Trade Treaty (ATT) was adopted by the United Nations General Assembly on 2 April 2013, entering into force on 24 December 2014. As of 1 August 2024, 115 States had ratified or acceded to the ATT and a further 27 were signatories. The ATT is the first global treaty to regulate the transfer of (almost all) conventional weapons.The second edition of The Arms Trade Treaty: A Commentary brings the legal interpretation of the treaty up to date after a decade of State practice. During that time, the legality of many transfers of conventional weapons has been contested, both under the terms of the treaty itself and under the rules of customary international and domestic law. The new commentary discusses the legality of arms transfers in connection with situations such as Russia-Ukraine and Israel-Palestine. It considers which weapons fall within the scope of the treaty-and which do not. The commentary describes, analyses, and comments on each of the treaty's 26 articles in turn, providing also background on the legal context for the transfer of conventional arms. The authors participated in the negotiation of the ATT and have followed its implementation closely from a range of vantage points, ensuring they offer expert insight on the treaty. The first edition of the commentary has been cited in domestic court proceedings in both pleadings and judgments in several countries, and has become the leading reference source on the ATT.