Article 51 of the UN Charter

Article 51 of the UN Charter provides for the right of countries to engage in self-defence, including collective self-defence, against an armed attack (including cyber-attacks). The Charter of the United Nations (also known as the UN Charter) of 1945 is the foundational treaty of the United Nations, an intergovernmental organisation.

The United Nations was established after World War II and the ultimate failure of diplomacy despite the existence of the League of Nations in the years between the First and Second World War. The Security Council was thus granted broad powers through Chapter VII of the UN Charter as a reaction to the failure of the League.

The UN Charter

The Charter of the United Nations (also known as the UN Charter) of 1945 is the foundational treaty of the United Nations, an intergovernmental organisation. The UN Charter articulated a commitment to uphold human rights of citizens and outlined a broad set of principles relating to achieving “higher standards of living”, addressing “economic, social, health, and related problems”, and “universal respect for, and observance of, human rights and fundamental freedoms for all without distinction as to race, sex, language, or religion”.

The Charter of the United Nations was signed on June 26, 1945, in San Francisco (United States of America), at the conclusion of the United Nations Conference on International Organization, and came into force on October 24, 1945. The Statute of the International Court of Justice is an integral part of the Charter.

As a charter (a written constitution or description of an organisation’s functions), it is a constituent treaty, and all members are bound by its articles. Furthermore, Article 103 of the Charter states that obligations to the United Nations prevail over all other treaty obligations: “In the event of a conflict between the obligations of the Members of the United Nations under the present Charter and their obligations under any other international agreement, their obligations under the present Charter shall prevail”.

Article 51 of the UN Charter

Chapter VII of the United Nations Charter sets out the UN Security Council’s powers to maintain peace. It allows the Council to “determine the existence of any threat to the peace, breach of the peace, or act of aggression” and to take military and non-military action to “restore international peace and security”.

Chapter VII also gives the Military Staff Committee (the United Nations Security Council subsidiary body whose role, as defined by the United Nations Charter, is to plan UN military operations and assist in the regulation of armaments) responsibility for strategic coordination of forces placed at the disposal of the UN Security Council. It is made up of the chiefs of staff of the five permanent members of the Council.

The UN Charter’s prohibition of member states of the UN attacking other UN member states is central to the purpose for which the UN was founded in the wake of the destruction of World War II: to prevent war. This overriding concern is also reflected in the Nuremberg Trials’ concept of a crime against peace “starting or waging a war against the territorial integrity, political independence or sovereignty of a state, or in violation of international treaties or agreements” (crime against peace), which was held to be the crime that makes all war crimes possible.

The United Nations was established after World War II and the ultimate failure of diplomacy despite the existence of the League of Nations in the years between the First and Second World War. The Security Council was thus granted broad powers through Chapter VII of the UN Charter as a reaction to the failure of the League. These broad powers allow it to enjoy greater power than any other international organisation in history. It can be argued that the strong executive powers granted to it give it the role of “executive of the international community” or even of an “international government”.

Chapter VII of the UN Charter on “Action with respect to Threats to the Peace, Breaches of the Peace, and Acts of Aggression”, Article 51, states that “Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security”.

Article 51 provides for the right of countries to engage in self-defence, including collective self-defence, against an armed attack (including cyber-attacks). This article was the impetus for much international pact-making and has been cited by the United States as support for the Nicaragua case and the legality of the Vietnam War. According to that argument, “although South Vietnam is not an independent sovereign State or a member of the United Nations, it nevertheless enjoys the right of self-defense, and the United States is entitled to participate in its collective defense”. Article 51 has been described as difficult to adjudicate with any certainty in real-life.

This Article 51 of the UN Charter is particularly vague: it does not define what constitutes an attack. Is the seizure of ships or aircraft an attack? Is the accidental or intentional violation of another country’s airspace an attack? Is industrial espionage an attack? Is a spy satellite taking photographs of military installations an attack? It does not define what constitutes an armed attack. For example, is a cyber-attack an armed attack?

It does not define “collective self-defence”. Does the attacked nation need to request assistance or can other nations pre-emptively intervene and claim their intervention constitutes collective self-defense? Requiring the attacked nation to request assistance might seem like the most responsible position, but this requires that the United Nations Security Council determine who the original aggressor and defender are. This determination may not be possible or delivered in a timely manner.

Article 51 of the United Nations Charter is sufficiently vague to allow states to assert their right to self-defense without escalating a conflict. While either side in a conflict may see the other as the aggressor acting beyond mere self-defense, Article 51 is vague enough that neither side can prove the other has acted offensively. This vagueness can aid in, if not the de-escalation of conflicts, preventing the rapid escalation of conflicts.

The militarisation of outer space

As space technology develops into more sophisticated areas such as space planes and a variety of space-based platforms with the potential capability to carry weapon systems, the issue of space as a theatre of war is a now a pressing issue that needs to be addressed. It is interesting to understand the tenets of the UN Charter against the landscape of the “peaceful purposes” mantra that underpins the Space Law regime.

Let’s recall that Article IV of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (entered into force on October 10, 1967) enounces that “States Parties to the Treaty undertake not to place in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner. The Moon and other celestial bodies shall be used by all States Parties to the Treaty exclusively for peaceful purposes. The establishment of military bases, installations and fortifications, the testing of any type of weapons and the conduct of military manoeuvres on celestial bodies shall be forbidden. The use of military personnel for scientific research or for any other peaceful purposes shall not be prohibited. The use of any equipment or facility necessary for peaceful exploration of the Moon and other celestial bodies shall also not be prohibited”.

In regard to the “peaceful purposes” mantra that underpins the Space Law regime, how to interpret Article 51 of the UN Charter? We hope these questions will be discussed at the Legal Subcommittee of the United Nations’ Committee on the Peaceful Uses of Outer Space (COPUOS).