International Law: Detailed Study Notes on the Use of Force and the UN Collective Security System

Fundamental Distinctions in the Use of Force: Jus ad Bellum vs. Jus in Bello

  • International law maintains a fundamental distinction between two categories of rules regarding the use of force:
    • Jus ad Bellum: These are the rules concerning when and for what purpose a State may lawfully use force against another State. It relates to the State’s political decision to initiate force.
    • Jus in Bello (International Humanitarian Law): These are the rules relating to how military hostilities must be carried out once they have begun. It concerns the implementation of the decision to use force.
  • Illustrative Example (2022 Russian Invasion of Ukraine):
    • The legality of the Russian Federation's decision to invade Ukraine is a matter of jus ad bellum.
    • The legality of the conduct of Russian soldiers during the subsequent hostilities (e.g., treatment of prisoners, targeting) is a matter of jus in bello.

Historical Overview of the Use of Force

  • Classic International Law: Use of force was traditionally intended as war-type violence. It was viewed as a lawful and common means of dispute resolution in international relations.
  • Progressive Erosion: Since the end of the First World War, there has been a systematic dismantlement of the conception of war as a lawful tool.
  • The League of Nations (Previous Attempt 1):
    • Article 10: Members undertook to respect and preserve the territorial integrity and existing political independence of all members against external aggression.
    • Article 12: Members agreed to submit disputes likely to lead to a rupture to arbitration, judicial settlement, or enquiry by the Council. They agreed "in no case to resort to war until three months after the award by the arbitrators or the judicial decision, or the report by the Council."
  • The Briand-Kellogg Pact (Previous Attempt 2):
    • Article I: High Contracting Parties solemnly declared they condemn recourse to war for solving international controversies and renounce it as an instrument of national policy in their mutual relations.
    • Article II: Agreed that the settlement of all disputes, regardless of nature or origin, shall never be sought except by "pacific means."

The UN Charter and the Prohibition of Armed Force

  • Preamble: The United Nations is determined to "save succeeding generations from the scourge of war," noting that war twice in the same lifetime brought untold sorrow to mankind.
  • Article 1: Lists the maintenance of international peace and security as a primary aim of the UN.
  • Article 2.3: Requires all Members to settle international disputes by peaceful means so that peace, security, and justice are not endangered.
  • Article 2.4 (The General Ban): "All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations."

The Scope and Legal Status of the Prohibition on Force

  • Legal Nature: As clarified by the International Court of Justice (ICJ) in the Nicaragua case (1986), the prohibition of the use of force is not only a treaty rule but also a rule of customary international law and a jus cogens (peremptory) provision.
  • Definition of Force: While highly debated, the prevailing view is that "force" is limited to military force. Political or economic coercion might violate the principle of non-intervention, but they do not violate the prohibition on the use of force under Article 2(4).
  • International Relations Scope: The prohibition applies to force used by States against other States (e.g., against territory, ships, or aircraft). It does not apply to military force used within a State's own territory (e.g., internal insurgencies or government action against rebels).
  • International Organizations: There is increasing consensus that the rule is also binding upon international organizations.

The Threat of the Use of Force

  • Nicaragua v. USA (1986) ICJ Findings:
    1. The act of a State arming itself does not per se constitute a "threat" under Article 2(4).
    2. A threat must consist of an explicit announcement of the use of armed force conditioned upon the occurrence or non-occurrence of a specific event or behavior.
  • Nuclear Weapons Advisory Opinion (1996): The ICJ clarified that any threat of force is prohibited if the actual use of that force would violate international law. There is a direct legal link between the legality of the threat and the legality of the use.

The UN Collective Security System (Chapter VII)

  • Primary Responsibility: Under Article 24, the Security Council (UNSC) has the main responsibility for maintaining international peace and security. Force authorized by the Council is an exception to Article 2(4).
  • Article 39 (The Trigger): The UNSC must determine the existence of a "threat to the peace, breach of the peace, or act of aggression" before taking action.
  • Broadening the Definition of "Threat": A 1992 Presidential Statement clarified that non-military sources of instability (economic, social, humanitarian, ecological) can constitute threats to peace.
  • Article 40 (Provisional Measures):
    • Measures intended to prevent the aggravation of a situation (e.g., a cease-fire).
    • Characteristics: Precautionary, impartial, and without prejudice to the rights or claims of the parties.
    • Status: Not strictly binding, but the Council takes note of failure to comply when deciding on subsequent measures.
  • Article 41 (Non-Forcible Measures):
    • Measures not involving armed force to give effect to Council decisions.
    • Examples: Complete/partial interruption of economic relations, severing of diplomatic relations, interruption of rail, sea, air, and radio communications.
    • Modern Practice: Includes "Smart Sanctions" (freezing funds, entry/transit bans) and the establishment of International Criminal Tribunals.
  • Article 42 (Forcible Measures):
    • If Article 41 measures are inadequate, the SC may take action by air, sea, or land forces (e.g., demonstrations, blockades).
    • Monopoly on Management: Originally, Articles 43-47 intended the SC to have military/strategic management monopoly, but in practice, the SC removes the prohibition by authorizing "coalitions of the willing" or Regional Organizations to use "all necessary means."

Authorizations and Case Studies

  • Requirements for Lawful Authorization:
    1. Must be granted ex ante (before force is used).
    2. Must explicitly allow the use of force.
    3. Must establish the duration and/or objective.
    4. Must remain under the effective control of the Council.
  • UNSC Resolution 1973 (2011) - Libya:
    • Authorized the use of force to protect civilians.
    • Mandated: Immediate cease-fire, "all necessary measures" to protect civilians, establishment of a "No-Fly Zone," and a strengthened arms embargo.
    • Limitations: Specifically did not allow for territorial occupation or regime change (the overthrow of Gaddafi).

Peacekeeping Operations

  • Peacekeeping is not explicitly provided for in the UN Charter; it developed through UN practice and represents a different category than Article 42 measures.
  • 1st Generation (Traditional): Requires consent of all parties; remains impartial; use of force only for self-defense; uses light armaments as separation forces.
  • 2nd Generation (Peace-making): Includes civil components for tasks like demobilizing fighters, destroying weapons, overseeing electoral processes, and training local police.
  • 3rd Generation (Peace-enforcement): Focused on protection of civilians or sensitive areas; includes the possibility of using force for mandate protection.