This chapter provides an overview of the legal framework governing unlawful acts at sea and their suppression. The point of departure is the analysis of the United Nations Convention on the Law of the Sea (UNCLOS), which was opened for signature in Montego Bay on December 10, 1982, with specific reference to the rights and duties of States concerning the different marine zones, as provided. Then, the analysis focuses on the Convention for the Safety of Life at Sea (SOLAS). The Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation Platforms (SUA Convention), adopted on March 10, 1988, and its 2005 Protocols related to unlawful acts against the Safety of Maritime Navigation and the Safety of Fixed Platforms are examined. Attention is paid to the additional protocols supplementing the United Nations Convention against Transnational Organized Crime, adopted within the framework of the United Nations Office on Drugs and Crime (UNODC), relating to transnational crimes at sea. After providing an overview of the main conventional instruments, the chapter focuses on the primary legal documents enacted by the United Nations and the International Maritime Organization that address the issue at stake. The domestic practice of some States could finally complete the framework.