text: Chapter 1
  General Background and Basic Principles of the Law of
  Armed Conflict
  Certain basic principles are foundational to a full understanding of LOAC, rules of
  engagement, and Army and Marine Corps doctrine. This chapter examines the law
  governing the resort to the use of armed force (jus ad bellum), the purpose and
  applicability of LOAC in armed conflict and its relationship with other law. After
  examining the basic LOAC principles, this chapter discusses the classes of persons
  distinguished within LOAC along with their basic rights, responsibilities, and
  liabilities. This chapter concludes with a discussion of the tools for implementation of
  LOAC, such as the role of protecting powers and humanitarian organizations within
  LOAC, when LOAC no longer applies, and the relationship with human rights law.
  INTERNATIONAL LAW AND USE OF FORCE IN INTERNATIONAL
  RELATIONS
  1-1. International law principally governs the relations between States both in peacetime and during armed
  conflict. Jus ad bellum is that part of international law that regulates the circumstances in which States
  may resort to the use of force in international relations. Jus in bello is that part of international law
  relating to the conduct of hostilities and the protection of war victims, from combatants who are
  wounded and out of combat, to prisoners of war and civilians.
  1-2. Article 2(4) of the United Nations (UN) Charter provides that States are required to refrain in their
  international relations from the threat or use of force against the territorial integrity or political independence
  of any State. There are circumstances in which the resort to force will not violate this prohibition, which
  include when the use of force is authorized by the UN Security Council, when it is undertaken with the
  consent of the territorial State, and when it is undertaken in the lawful exercise of the inherent right of self-
  defense (See DOD Law of War Manual, 1.11.4). For example, the United States has used armed force
  pursuant to an authorization in a UN Security Council Resolution and pursuant to its inherent right of
  individual or collective self-defense against an armed attack.
  1-3. The decision to resort to the use of force in international relations is one that is decided at the national
  level. Because this publication is intended for Soldiers and Marines operating at lower echelons, it will focus
  on the jus in bello principle, that is, the international law relating to the conduct of hostilities and the
  protection of war victims, which as discussed in paragraph 1-4 below, is known as LOAC.
  LEX SPECIALIS–THE LAW OF ARMED CONFLICT
  1-4. LOAC, also referred to as the law of war, is that part of international law that regulates the conduct of
  hostilities and the protection of war victims both in international and non-international armed conflict;
  belligerent occupation; and the relationship between belligerent, neutral, and non-belligerent States (see DOD
  Law of War Manual, 1.3; JP 3-84). The legal maxim lex specialis derogat legi generali, also known as the
  principle of specialty, provides that as a rule, the special law overrides the general law. This means if an
  action is regulated by both a general provision and a specific one, the latter applies, as it is more specifically
  directed toward the action. LOAC is the lex specialis of armed conflict; it is the controlling body of law and
  provides the legal standards that apply to the conduct of hostilities and the protection of war victims.