LWN158: Public International LawSEMINAR WEEK 6

JUS AD BELLUM

Objectives this week

To critically examine the international legal norms governing the use of force including: The prohibition on the use of force contained in art 2(4) of the

UN Charter; The right to self-defence, including individual and collective self-

defence, anticipatory and pre-emptive self-defence; Collective security under Ch VII of the UN Charter (see also week

9). To consider the implications of other possible justifications for the

use of force, including the doctrines of responsibility to protect and humanitarian intervention.

Disambiguation

International law includes two areas relating to the use of force:

1. Jus ad bellum – laws relating to the commencement of armed conflict

2. Jus in bello – laws relating to the conduct of armed conflict (or international humanitarian law)

This week: jus ad bellum Next week: jus in bello

United Nations Charter: Prohibition on the Threat or Use of Force

UN Charter article 2(3): “All Members shall settle their international disputes by peaceful means in such a manner that international peace and security, and justice, are not endangered.”

Article 2(4): “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.”

Customary prohibition on use of force

Nicaragua (Merits) decision confirms that the prohibition in article 2(4) is binding on all states as a matter of customary international law

Also confirmed principle of non-intervention in the domestic affairs of other states

Based on principles of sovereign equality of all states (in article 2(1)) and territorial sovereignty (Corfu Channel (Merits))

Principle of non-intervention includes both armed and non-armed activities

Where an intervention involves use of force it will breach both articles 2(1) and 2(4).

What is ‘use of force’?

Definition comes from Declaration on Principles of International Law Concerning Friendly Relations and Cooperation Among States in Accordance with the United Nations Charter (General Assembly Resolution 2625, 24 October 1970)

Declaration expands on the prohibition contained in art 2(4) and sets out a number of specific duties which States have, including duties to refrain from: propaganda for wars of aggression threat or use of force to violate existing boundaries of another State or as means of

solving international disputes threat or use of force to violate international lines of demarcation, such as armistice

lines acts of reprisal involving use of force forcible action which deprives people of right to self-determination, freedom and

independence

Declaration on Friendly Relations:

organising or encouraging the organisation of irregular forces or armed bands, including mercenaries, for incursion into the territory of other States

organising, instigating, assisting or participating in acts of civil strife or terrorist acts in another State, or acquiescing in organised activities within its territory directed towards the commission of such acts, where they involve threat or use of force

Declaration also specifies that wars of aggression constitute crime against peace to which international responsibility attaches (but ‘aggression’ not defined)

Resolution expressly avoids ‘enlarging or diminishing in any way the scope of the provisions of the Charter concerning cases in which the use of force is lawful’

Aggression

Some uses of force will be aggression Declaration on Friendly Relations: ‘aggression’ = crime against peace, but not

defined Resolution on the Definition of Aggression (GA Resolution 3314 of 14

December 1974): “the use of armed force by a State against the sovereignty, territorial

integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations”

Declaration on the Definition of Aggression

Art 3: lists certain acts said to qualify as acts of aggression.

(a) Invasion or attack by armed forces on territory of another State, or military occupation, or annexation of territory

(b) Bombardment or use of weapons against territory of another State

(c) Blockade of ports or coasts of another State

(e) Use of armed forces which are by arrangement within the territory of another State in a manner inconsistent with the terms of that arrangement

(f) Allowing territory to be used by another State to perpetrate act of aggression against a third State

(g) The sending, by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount to the acts listed above, or its substantial involvement therein.

Definition of Aggression cont/...

Art 4: SC may determine other acts to constitute aggression (list is not exhaustive)

Acts listed in art 3 have been recognised as reflecting customary international law (Nicaragua (Merits) case

A State will not be able to evade legal responsibility for aggression by using armed bands, mercenaries, irregulars or terrorists with no formal link to the State, provided the State has ‘sent’ them or has been ‘substantially involved’ in their sending.

Definition of Aggression in the Rome Statute

Art 8 bis: “For the purpose of this Statute, ‘crime of aggression’ means the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations.”

Aggression and the Rome Statute of the International Criminal Court

Art 5: ICC has jurisdiction over the crime of aggression Rome Statute entered into force in 2002 but jurisdiction

over aggression was not to commence until parties had agreed on definition of crime

2010: first Review Conference for parties to Rome Statute in Kampala, Uganda

Adopted article 8 bis: definition of aggression Court won’t be able to exercise jurisdiction over the crime

until after 1 January 2017, when states are to make a decision on activation of jurisdiction.

Two views on UN Charter Art 2(4)

Prohibits 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.”

Two possible interpretations:

1. Narrow view: Only prohibits use of force where intended to affect territorial integrity or political independence – so might not include force used to address gross violations of human rights

2. Broad view: Completely prohibits use of force unless a specific exception can be found in Charter, on the basis that a complete view of Statehood requires that any use of force would be against territorial integrity.

Second view has more support from UN and state practice – that is, use of force is unlawful unless it falls within one of the specific exceptions.

Exceptions to the prohibition on the use of force

Two exceptions in UN Charter

1. Self-defence

2. Collective measures authorised by the Security Council under Chapter VII

And also possible customary exceptions:

3. Invitation by state

4. Protection of nationals abroad

5. Humanitarian intervention

6. Responsibility to protect

Self-defence: UN Charter art 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.”

An inherent right to self-defence

Art 51: “inherent right” – so not created by UN Charter but existing right

What is position under customary international law? The Caroline (1837) – test for lawful self-defence:

There must be a necessity of self-defence which is both instant and overwhelming

There must be no choice of means There must be no moment for deliberation Force used in self-defence must not be unreasonable or excessive

Inherent right to self-defence cont/...

Nicaragua (Merits) case: confirmed right of self-defence in customary international law but must be:

1. proportionate to attack, and

2. necessary to respond to it.

No mention of requirement for no choice of means or moment for deliberation.

Nuclear Weapons Advisory Opinion: confirmed customary law requirements of necessity and proportionality (split decision)

Art 51: “Armed attack”

Article 51 preserves right of self defence if an armed attack occurs. What constitutes an ‘armed attack’? Nicaragua (Merits):

not merely any action by regular armed forces across an international border

Includes sending armed bands, groups, irregulars, mercenaries by a State to carry out acts of armed force of such gravity as to amount to actual armed conduct

Or substantial involvement therein Based on definition of ‘aggression’ in article 3(g) of GA Res 3314, which the

court considered to be reflective of customary international law

“Armed attack” cont/...

Nicaragua (Merits): introduces test of ‘scale and effects’: in order for an act of aggression to equate to an armed attack sufficient to justify self-defence, it must be on a scale and produce effects greater than a mere frontier incident

Sending by a State of armed bands to the territory of another State could be an armed attack, but merely providing weapons or other support would not be

But court noted that providing such support could be an unlawful threat or use of force, or an unlawful intervention in the internal affairs of another state, it just wouldn’t be an ‘armed attack’ sufficient to justify self-defence.

So: not every use of force = ‘armed attack’ which would trigger right to self-defence

But an accumulation of events may amount to an armed attack, even where each event on its own would be inadequate (Oil Platforms case)

Attribution of Armed Attacks

Nicaragua (Merits): Right to self-defence does not arise where armed attack is carried out by groups whose conduct is not attributable to a state.

Confirmed in Armed Activities in the Congo decision – no evidence that use of force by rebels was attributable to the Congo.

Attacks by non-state actors (eg terrorists) can trigger right to self-defence where there is sufficient evidence that sovereign state is providing support or tolerating activities (see Security Council resolutions following 9/11).

Anticipatory self-defence?

Art 51: “if an armed attack occurs” Does this mean that a State can’t resort to force in self-defence unless

an armed attack has actually commenced against them, even where there is strong evidence of an imminent attack?

Advantage of strict approach: certainty that attack has occurred; clarity and transparency regarding motives of defending state

Disadvantages: strengthens the hand of an aggressor; denies advantage of pre-emptive strike.

Anticipatory self-defence and the Caroline principle

Customary self-defence as set out in the Caroline doesn’t include words ‘if an armed attack occurs’ – instead allows self-defence where the need is ‘instant and overwhelming’.

This has been argued to support a right of anticipatory self-defence, allowing a state to act where threat of armed attack is imminent

Anticipatory self-defence would still be limited by principles of necessity and proportionality

This approach seems to be ruled out by language of art 51 which limits self-defence to situations where armed attack has occurred, BUT article 51 says that nothing interferes with the ‘inherent’ right to self defence.

So: is the ‘inherent’ right the same as the Caroline concept of anticipatory self-defence?

Anticipatory self-defence cont/…

Nicaragua: the ICJ didn’t rule specifically on lawfulness of response to imminent attack, but did confirm that existence of an ‘armed attack’ is a prerequisite for self-defence – other threat to national interests not involving an armed attack would not be sufficient.

Still doubt whether an anticipatory use of force in response to an imminent armed attack would be lawful.

Some have argued that customary position now is more narrow than Caroline principle Brownlie: contemporary state practice has rejected the flexible approach in Caroline

Henkin: limited to actual armed attack – no anticipatory right exists

Triggs: adopting a broad definition of ‘armed attack’ might remove the need to rely on anticipatory right – would include situation where attack is ‘genuinely imminent’

Other scholars: no sense requiring state to wait for attack to occur if they know it’s inevitable

Anticipatory self-defence cont/…

If anticipatory self-defence is lawful, there must be an ‘imminent’ attack Distinguish ‘pre-emptive’ self-defence, which would allow action before

attack is imminent. Concept of ‘imminent attack’ implies that attack is inevitable Usually understood in context of traditional military action – where

preparations for war are readily observable Can be more difficult to establish for more modern forms of force

Cyber attacks? Terrorist attacks?

Might need to refer to pattern of past attacks to establish imminence Support for pre-emptive right is more controversial – see Bush Doctrine and

justification for invasion of Iraq in 2003 (weapons of mass destruction)

Anticipatory self-defence cont/…

If anticipatory self-defence is permitted, it must still be necessary and proportionate

This can be problematic, as it’s difficult to establish what a necessary or proportionate response is to an attack which hasn’t yet occurred

This is even more difficult with a pre-emptive use of self-defence, as the armed attack is even more remote and uncertain

Collective self-defence

Art 51: individual or collective self-defence When can a State use force in defence of another State which claims to have been

attacked? An act of collective self-defence must meet all requirements of individual self-defence:

An armed attack

Proportionality

Necessity

Observance of humanitarian law

Additionally, the victim State must have requested the assistance of the third State (Nicaragua (Merits) case)

Recent action in Syria against IS is example of collective self-defence, requested by Iraq.

Second exception: Security Council Authorisation of Use of Force (Ch VII)

A State may use force against another State if it has received prior authorisation from the Security Council, which has primary responsibility for the maintenance of international peace and security (Art 24(1))

Art 39: Security Council shall determine existence of any threat to peace, breach of peace or act of aggression and make recommendations

Art 41: Security Council shall decide what measures not involving the use of armed force are to be employed to give effect to its decisions.

Article 42: authorisation of the use of force

“Should the Security Council consider the 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. Such action may include demonstrations, blockade, and other operations by air, sea or land forces of Members of the United Nations.”

Article 43: Members of the UN undertake to provide armed forces and other assistance to maintain international peace and security

Other exceptions: Invitation by State

Where use of force is carried out with the consent or invitation of the State concerned it will not be a violation of article 2(4).

Example: Regional Assistance Mission to the Solomon Islands (RAMSI) Solomon Islands requested assistance from other States to provide

internal security and stability in the face of breakdown of internal law and order

Forces provided by Australia, NZ, Fiji, PNG, Samoa & Tonga

Other exceptions: Protections of Nationals Abroad

State practice supports limited right to use force against another state to protect nationals – has been argued as justification by some states but remains controversial (eg in Tehran Hostages case)

Rationale is that use of force to protect nationals is an extension of the right to self-defence.

Should first attempt to get State in whose territory they are located to intervene. Where that State is unwilling or unable to protect them, should try to obtain its permission to intervene

Should seek assistance of UN where that would be adequate, but if UN not able to act in time and need for instant action is manifest, could use force, provided it was limited to securing safe removal of nationals and was not used as a pretext for other force or action.

Protection of nationals abroad cont/...

Use of force would still need to be necessary and proportionate. Huber J in Spanish Zones of Morocco: right to intervene might

exist, but presupposes that other means of protection are inadequate

US Diplomatic and Consular Staff in Tehran Case (US v Iran) (Tehran Hostages) : ICJ didn’t rule explicitly on the legality of the operation but did comment that intervention is ‘of a kind calculated to undermine respect for the judicial process in international relations’ – suggests that ICJ is likely to view intervention to protect nationals as unacceptable except as a last resort.

Possible exception: Humanitarian Intervention

Controversial doctrine which posits that use of force may be justified where it is necessary to address overwhelming human catastrophe, even without Security Council approval.

No right exists in international law, either in treaty or custom – strictly speaking would be violation of art 2(4)

But some scholars (and some states) have argued that an exception ought to be made in order to address situations where use of force is necessary but Security Council has failed to act – strict conformity with the law can’t be justified in the face of human catastrophe.

Humanitarian intervention cont/...

No clear ruling from ICJ on legal status of humanitarian intervention but some dicta: Nicaragua and Tehran Hostages: ICJ commented that protection of human

rights in those cases was incompatible with the use of force which actually occurred – couldn’t justify use of force on humanitarian grounds

Accepting a right of humanitarian intervention would also be a dangerous precedent – would risk abuse by powerful states

Suggests that even if right did exist, use of force would still have to be necessary and proportionate.

Legality of the Use of Force case – intervention in Kosovo: ICJ unable to decide the legal issues because it had no jurisdiction to hear claims by Serbia and Montenegro.

Responsibility to Protect

“Collective international responsibility to protect which is exercisable by the SC authorising military force as a last resort in situations of genocide, ethnic cleansing, or serious violations of humanitarian law which the state has proved powerless or unwilling to prevent.”

Rationale is that a State has a responsibility to protect its citizens but where a state fails to protect, the responsibility should fall to the international community

Usually considered to be limited to mass atrocities like war crimes, CAH and genocide.

Military force could be used if peaceful means have failed. Still requires approval by the Security Council :

operates more as reconceptualisation of Ch VII powers than separate exception to article 2(4).

Intended to shift the way States feel about Ch VII mechanisms and when they should be used