This publication sets out fundamental principles of international and domestic law that govern U.S. naval operations at sea. Chapters 1 through 4 provide an overview and general discussion of the law of the sea, including: 1. Definitions and descriptions of the jurisdiction and sovereignty exercised by States over various parts of the world's oceans 2. The international legal status and navigational rights of warships and military aircraft 3. Protection of persons and property at sea 4. The safeguarding of national interests in the maritime environment. Chapters 5 through 12 set out principles of law of special concern to the naval commander during any period in which U.S. naval forces are engaged in armed conflict. Although the primary emphasis of these chapters is on the conduct of naval warfare, relevant principles and concepts common to the whole of the law of war are discussed. PURPOSE This publication is intended for the use of operational commanders and supporting staff elements at all levels of command. It is designed to provide officers in command and their staffs with an overview of the rules of law governing naval operations in peacetime and during armed conflict. The explanations and descriptions in this publication are intended to enable naval commanders and their staff to comprehend more fully the legal foundations upon which the orders issued to them by higher authority are premised and better understand the commander's responsibilities under international and domestic law to execute their missions within that law. Officers in command of operational units are encouraged to utilize this publication as a training aid for assigned personnel. This publication provides general information and guidance, which is generally augmented, limited, or given further clarity by directives issued by operational commanders and their subordinates. It does not supersede guidance issued by the chain of command. It is not directive or a comprehensive treatment of the law. It is not a substitute for definitive legal guidance provided by judge advocates and others responsible for advising commanders on the law. INTERNATIONAL LAW For purposes of this publication, international law is defined as that body of rules that States consider binding in their relations with one another. International law is created by States. It derives from the practice of States in the international arena and from international agreements between States. International law provides stability in international relations and an expectation that certain acts or omissions will result in predictable consequences. If one State violates the law, it may expect that others will reciprocate. Consequently, failure to comply with international law ordinarily involves greater political and economic costs than does observance. States comply with international law, because it is in their interest to do so. Like most rules of conduct, international law is in a continual state of development and change. This publication seeks to accurately describe the state of international law on the date of the publication's issuance. The primary sources of international law are customary international law and international agreements.