The Use of Force and Collective Security

Self-defence: article 51

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.

The conditions in the text.

An armed attack must occur. Not a threat, not a border incident of any kind, but an armed attack. Whether the words permit action against an attack that is imminent but not begun is the anticipatory self-defence question, and the text points against it while a body of State practice and the older law point the other way. An answer should state the text first and the controversy second.

Individual or collective. Collective self-defence permits other States to come to the aid of the victim, and the requirement generally accepted is that the victim declare itself attacked and request assistance.

Until the Security Council has taken measures necessary. The right is provisional, and it yields to the Council's action.

Measures must be immediately reported to the Council. Failure to report does not by itself destroy the right, but it is evidence against a State claiming to have acted in self-defence.

Inherent right. The word inherent, droit naturel in the French text, preserves the customary right alongside the Charter, which is why the customary conditions continue to apply.

The customary conditions: necessity and proportionality. They are not in the text of article 51 and they bind all the same. The response must be necessary, in the sense that no peaceful means would serve, and proportionate to the attack repelled. The classic formulation comes from the Caroline correspondence of 1837, requiring a necessity of self-defence instant, overwhelming, leaving no choice of means and no moment for deliberation.

Chapter VII: the Council's enforcement powers

The determination, article 39

The Security Council shall determine the existence of any threat to the peace, breach of the peace, or act of aggression and shall make recommendations, or decide what measures shall be taken in accordance with Articles 41 and 42, to maintain or restore international peace and security.

Article 39 is the gate to the whole of Chapter VII. Nothing binding follows until the Council makes the determination, and the determination is the Council's own: the Charter defines none of the three terms, and the Council has read threat to the peace very widely, extending it to internal conflicts, to humanitarian catastrophes, to terrorism in general terms, and to the proliferation of weapons.

Provisional measures, article 40

In order to prevent an aggravation of the situation, the Council may, before making recommendations or deciding upon measures under article 39, call upon the parties concerned to comply with such provisional measures as it deems necessary or desirable. Such measures shall be without prejudice to the rights, claims, or position of the parties, and the Council shall duly take account of failure to comply.

The standard provisional measure is a ceasefire and a withdrawal to previous positions.

Measures short of force, article 41

The Council may decide what measures not involving the use of armed force are to be employed to give effect to its decisions, and may call upon Members to apply them. These may include complete or partial interruption of economic relations and of rail, sea, air, postal, telegraphic, radio, and other means of communication, and the severance of diplomatic relations.

The word "may include" is what has carried modern practice. The list is illustrative, and the Council has treated article 41 as authorising measures the drafters never contemplated, including the creation of the international criminal tribunals for the former Yugoslavia and for Rwanda, targeted financial sanctions against individuals, and arms embargoes.

Force, article 42

Should the Council consider that measures provided for in article 41 would be inadequate or have proved to be inadequate, it may take such action by air, sea, or land forces as may be necessary to maintain or restore international peace and security, including demonstrations, blockade, and other operations by the forces of Members.

Note the condition. Article 41 measures must be considered inadequate or have proved inadequate. The Council makes that judgment.

The forces that never came: articles 43 to 47

Article 43. All Members undertake to make available to the Security Council, on its call and in accordance with a special agreement or agreements, armed forces, assistance, and facilities, including rights of passage. The agreements were to govern numbers, types, readiness and location, to be negotiated as soon as possible on the Council's initiative, concluded between the Council and Members or groups of Members, and subject to ratification.

No article 43 agreement has ever been concluded.

Article 44. Where the Council has decided to use force, it shall, before calling on a Member not represented on it to provide forces, invite that Member, if it so desires, to participate in the decisions concerning the employment of its contingents.

Article 45. Members shall hold immediately available national air-force contingents for combined international enforcement action, within the limits of the article 43 agreements.

Article 46. Plans for the application of armed force shall be made by the Council with the assistance of the Military Staff Committee.

Article 47. There shall be established a Military Staff Committee to advise and assist the Council on its military requirements, consisting of the Chiefs of Staff of the permanent members or their representatives, responsible under the Council for the strategic direction of forces placed at its disposal, questions of command to be worked out subsequently. The Committee exists formally and has never performed the function the article gives it.

The consequence of articles 43 to 47 remaining unimplemented is the practice of authorisation: rather than commanding forces of its own, the Council authorises Members, or a coalition, or a regional organisation, to use all necessary means. That practice is not in the Charter's text, and it is now the ordinary way article 42 operates.

Carrying the measures out, articles 48 to 50

Article 48. The action required to carry out the Council's decisions shall be taken by all the Members or by some of them, as the Security Council may determine, and shall be carried out directly and through their action in the appropriate international agencies of which they are members.

Article 49. Members shall join in affording mutual assistance in carrying out the measures decided upon.

Article 50. Where preventive or enforcement measures are taken against a State, any other state, whether a Member or not, which finds itself confronted with special economic problems arising from the carrying out of those measures shall have the right to consult the Security Council about a solution. The right is to consult, and no more.

Regional arrangements: articles 52 to 54

Article 52(1). Nothing precludes regional arrangements or agencies for matters relating to the maintenance of peace and security appropriate for regional action, provided they and their activities are consistent with the Purposes and Principles.

Article 52(2) and (3), the duty of every effort at regional settlement first, and the Council's duty to encourage it, are set out in [Pacific Settlement of Disputes]. Article 52(4) preserves articles 34 and 35.

Article 53(1), the key rule. The Council shall, where appropriate, utilize such regional arrangements or agencies for enforcement action under its authority. But no enforcement action shall be taken under regional arrangements or by regional agencies without the authorization of the Security Council, with the historical exception for measures against an enemy state under article 107 or in arrangements directed against the renewal of aggressive policy by such a state.

So a regional organisation may not enforce on its own. It may settle disputes, and it needs authorisation to use force. Article 54 requires the Council to be kept fully informed of activities undertaken or in contemplation under regional arrangements.

Peacekeeping: the practice the Charter does not name

The Charter provides for enforcement, not for peacekeeping. Peacekeeping operations grew from practice, and their accepted foundations are the consent of the host State, impartiality, and the use of force only in self-defence and defence of the mandate. They have been established by the Council under article 29 as subsidiary organs and, on one occasion, by the General Assembly. The costs are expenses of the Organization apportioned under article 17(2).

A worked example

State AA invades State BB and occupies a province. State BB asks State CC for help. The Council meets, determines a breach of the peace, calls for a ceasefire, and later imposes an arms embargo. When that fails, it adopts a resolution authorising Member States cooperating with State BB to use all necessary means to restore the province. A regional organisation of which State AA is a member proposes to act on its own.

Is the invasion lawful? No. It is a use of force against the territorial integrity of State BB contrary to article 2(4), and article 2(4) also binds as custom and is generally regarded as peremptory.

May State BB defend itself? Yes. An armed attack has occurred, so article 51 preserves the inherent right of individual self-defence until the Council has taken measures necessary to maintain international peace and security, and the response must be necessary and proportionate.

May State CC help? Yes, as collective self-defence under article 51, on the generally accepted conditions that State BB has declared itself the victim of an armed attack and has requested assistance.

Must they report? Yes. Article 51 requires measures taken in the exercise of the right to be immediately reported to the Council.

The ceasefire call. Article 40 provisional measures, without prejudice to the rights, claims or position of the parties, with the Council to take due account of any failure to comply.

The arms embargo. Article 41, a measure not involving the use of armed force, binding on Members under article 25, and by article 48 to be carried out by all Members or by such of them as the Council determines. A neighbouring State ruined by the embargo has a right to consult the Council under article 50, and nothing more.

The authorisation to use all necessary means. Article 42 in its modern form. Since no article 43 agreement exists, the Council does not command forces and instead authorises Members to act, which is the practice that has replaced the Charter's design.

The regional organisation acting alone. Article 53(1) forbids enforcement action under regional arrangements without the authorisation of the Security Council. It may attempt pacific settlement under article 52(2); it may not enforce.

Change one fact: no armed attack has yet occurred, but State AA's forces are massing. Article 51 speaks of an armed attack occurring, so the text does not cover it, and whether anticipatory self-defence is lawful remains contested, with the Caroline requirement of a necessity instant, overwhelming, leaving no choice of means and no moment for deliberation as the classical test.

Distinctions table

What it does NOT mean

Article 2(4) is not confined to war. It covers any threat or use of armed force in international relations.

It does not cover economic coercion. That falls under non-intervention.

Article 51 does not create the right of self-defence. It preserves an inherent right and imposes conditions on its exercise.

Self-defence is not indefinite. It runs until the Council has taken the measures necessary.

Article 39 does not define its own terms. Threat to the peace, breach of the peace and act of aggression are for the Council.

Article 41 is not a closed list. The measures listed are examples.

A regional organisation cannot enforce alone. Article 53(1) requires Council authorisation.

Limits and criticism

The collective security system in articles 43 to 47 was never built, so the Charter's central design, a Council with forces at its disposal directed by a Military Staff Committee, exists only on paper, and enforcement depends on the willingness of individual States to act under authorisation.

Authorisation resolutions are drafted in open terms. All necessary means confers a discretion whose limits are contested, and once granted an authorisation is difficult to withdraw, since the withdrawal is itself subject to the veto.

Article 39 gives the Council an unreviewable discretion. What is a threat to the peace has expanded far beyond inter-State conflict, and no organ has power to say the Council has exceeded article 24(2).

The exceptions are under pressure. Claims of anticipatory self-defence, of self-defence against non-State actors on another State's territory, and of humanitarian intervention have all been asserted, none has been generally accepted, and the practical result is uncertainty in exactly the area where certainty matters most.

Quick revision

Article 2(4): refrain from the threat or use of force in international relations against territorial integrity or political independence or in any other manner inconsistent with the Purposes. Custom, and generally regarded as jus cogens. Corfu Channel: the alleged right of intervention is only the manifestation of a policy of force which cannot find a place in international law, and self-help fails because respect for territorial sovereignty is an essential foundation for international relations.

Two exceptions: article 51 and Chapter VII.

Article 51: inherent right of individual or collective self-defence if an armed attack occurs, until the Council has taken measures necessary, measures to be immediately reported. Customary conditions: necessity and proportionality; Caroline: instant, overwhelming, leaving no choice of means and no moment for deliberation.

Article 39: the Council determines a threat to the peace, breach of the peace or act of aggression. Article 40: provisional measures, without prejudice to rights, claims or position. Article 41: measures not involving armed force, including interruption of economic relations and communications and severance of diplomatic relations. Article 42: air, sea or land action where article 41 would be or has proved inadequate.

Articles 43 to 47: special agreements for forces, never concluded; Military Staff Committee of the Chiefs of Staff of the permanent members, never used as designed. Hence authorisation in practice.

Article 48: action by all Members or some, as the Council determines. Article 49: mutual assistance. Article 50: a State facing special economic problems has a right to consult.

Article 52: regional arrangements consistent with the Purposes and Principles. Article 53: no enforcement action by regional agencies without Council authorisation. Article 54: the Council to be kept fully informed.

Peacekeeping rests on consent, impartiality, and force only in self-defence and defence of the mandate.

Test yourself

1. State the prohibition in article 2(4) and explain each of its elements.

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 prohibition covers the threat as well as the use. It applies in international relations, so it does not reach a State's conduct within its own territory, which other bodies of law govern. Force means armed force, a reading supported by the Preamble, by Chapter VII and by the rejection at San Francisco of a proposal to include economic coercion. And the closing words prevent the qualification about territorial integrity and political independence from being read as a loophole, since force inconsistent with the Purposes of the Organization is prohibited whatever its declared object.

2. What are the conditions for the exercise of self-defence?

Article 51 requires that an armed attack occur, and preserves the inherent right of individual or collective self-defence until the Security Council has taken measures necessary to maintain international peace and security, requiring that measures taken be immediately reported to the Council and not affect its authority and responsibility. Because the right is described as inherent, the customary conditions continue to apply, namely necessity, in the sense that no peaceful means would serve, and proportionality to the attack repelled. The classical statement of necessity is in the Caroline correspondence of 1837, which required a necessity of self-defence instant, overwhelming, leaving no choice of means and no moment for deliberation. In collective self-defence it is generally required that the victim declare itself attacked and request assistance.

3. Set out the Security Council's powers under Chapter VII in order.

Article 39 requires the Council to determine the existence of a threat to the peace, breach of the peace or act of aggression, and to make recommendations or decide what measures shall be taken under articles 41 and 42. Article 40 permits it, before doing so, to call upon the parties to comply with provisional measures to prevent an aggravation of the situation, without prejudice to their rights, claims or position, taking due account of any failure to comply. Article 41 permits it to decide on measures not involving the use of armed force, which may include the complete or partial interruption of economic relations and of communications and the severance of diplomatic relations. Article 42 permits action by air, sea or land forces where it considers that article 41 measures would be inadequate or have proved inadequate. Articles 48 to 50 then govern implementation.

4. Why does the Council authorise Member States to use force rather than using forces of its own?

Because the Charter's machinery was never built. Article 43 required Members to undertake to make armed forces, assistance and facilities available to the Council under special agreements governing numbers, types, readiness and location, to be negotiated on the Council's initiative and ratified by the signatory States, and no such agreement has ever been concluded. Articles 45 to 47 depend on those agreements, and the Military Staff Committee established by article 47, composed of the Chiefs of Staff of the permanent members, has never performed the strategic direction the article assigns it. In their absence the Council has developed the practice of authorising Members, coalitions or regional organisations to use all necessary means, which is not provided for in the text and is now the ordinary way article 42 operates.

5. May a regional organisation take enforcement action?

Not on its own. Article 52(1) permits regional arrangements or agencies for matters relating to the maintenance of international peace and security which are appropriate for regional action, provided they and their activities are consistent with the Purposes and Principles. Article 52(2) requires Members entering into such arrangements to make every effort to achieve pacific settlement of local disputes through them before referring the dispute to the Council. But article 53(1) provides that the Council shall where appropriate use such arrangements for enforcement action under its authority, and that no enforcement action shall be taken under regional arrangements or by regional agencies without the authorisation of the Security Council, subject only to the historical exception concerning enemy states. Article 54 requires the Council to be kept fully informed of activities undertaken or in contemplation.

6. What is peacekeeping and where does the Charter provide for it?

The Charter does not provide for it at all. Peacekeeping developed in practice as something between the pacific settlement of Chapter VI and the enforcement of Chapter VII, and operations have been established by the Security Council as subsidiary organs under article 29 and on one occasion by the General Assembly under article 22. Its accepted foundations are the consent of the host State, the impartiality of the force, and the use of force only in self-defence and in defence of the mandate, which distinguish it from enforcement action, where none of the three applies. The costs of such operations are expenses of the Organization borne by the Members as apportioned by the General Assembly under article 17(2).