Jus Ad Bellum Lesson International Law

War And Peace in International Law History

* Foundational to Modern IL- e.g. Westphalia (pre 20th century, little IL beyond war and peace

* Yet IL often doubted most in this context

War

violence, coercion, state power- opposite of the law

But law relies on force:

Domestically: state monopoly on force

Internationally: no monopoly

* Force can uphold order-coercive enforcement of IL

* Legitimate use of force defined by IL- jus ad bellum

* Historically: broadly lawful

* Post 1945: largely banned

* Legitimate authority transferred to UNSC

Just war tradition

the idea that wars must be judged according to two categories of justice: (1) jus ad bellum, or the justness of war itself; and (when is war legal)(2) jus in bello, or the justness of each actor's conduct in war (how must wars be fought)

Early efforts to restrict right to wage war

Hague Convention

Convenant League of Nations

Kelogg Briand Pact

Hague Conventions

1899, 1906

* Law of Armed Conflict, but some jus ad bellum

* Formal "declaration of war" required (now obselete)

* Force banned to collect deby (Drago-Porter Convention)

*1st substantive limit on war

Convenant of League of Nations

1919

* Art. 16: an illegal war= act of war against all members

* Collective security

* War now a global concern (not just bilateral)

* Limited: no full ban on war+ no authority to enforce the peace

*Art. 13: disputes to be referred to PCIJ/arbitration

*3-month no-war cool-off period

* Art. 15: If Council deadlocks- states can do whatever

Kellogg-Briand Pact (1928)

a multi-nation treaty, sponsored by American and French leaders, that outlawed war.

Impact

*Short-term: ineffective (1930s invasions)

*Japan- Manuchuria (1931); Italy- Abyssinia (1935); Germany/USSR- Poland (1939)

* Long-term: legally significant

* Key weakness: inademplenti non est adimplendum

* If one party violated, others no longer bound- UN Charter (1945) closed the loophole

Inadimplenti non est adimplendum

If A violates a treaty, then B may do the same

Article 24 UN Charter

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.

What constitutes "use of force"?

Broader than "war"- most forms of military force

(What about economic coercion, cyber attacks?)

When is a "threat" to use force illegal?

* Hard to operationalize

Key critieria of UN Charter 24

* Against a state's "territorial integrity" or "political independence"

* Only in "international relations"

* Not force within states

* Classification (int'l vs. not) matters: different rules apply

When is use of force legal?

2 exceptions:

UN Security Council authorization collective security) only competent authority

Self-defense by states (main exception- Art. 51)

Paramount obligation under both UN Charter and CIL

* Now recognized as jus cogens

* Presumption of illegality

* Burden of proof on state using force- must prove legality of its action

The right of self-defense

* Only legal unilateral use of force w/out UNSC

*Nicargauga (1986): "exception" to general prohibition

* To be immediately reported to UNSC

* rare in practice

Inherent right

Inherent right

* Rooted to sovereignity + CIL

* Principles: Military necessity, Proportionality (not an excuse for long-term occupation

Scope: armed attack

* The narrower the scope of SD, the stronger the general ban on use of force

Legal standard: "armed attack"

*French version (Art 51): armed aggression- implies highrt threshold than "attack"

* UNGA Res. 3314 (1974) (defines "aggression- nonbinding)- only serious intentional use of force

e.g.: invasion. annexation, bombardment, blockade, attack on armed forces, etc.

ICJ case law

Nicaragua (1986): must be "most grave forms" of use of force

Armed Activities (2005): right to SD must be narrowly interpreted - not "general security interests"

Oil Platforms (2003): must be specifically directed at the state w/specific intent to harm it

So-- gravity threshold= must involve serious scale and effect

* Not minor incident, isolated border skirmishes

Use of force below the armed attack threshold?

* May violate Art 2 (4) but does not justify self-defense

Scope: non-state actors

Non-state actors can also carry armed attacks triggering Art. 51.

Irregular forces (e.g. militias, terrorists)

* Nicaragua (1986)

*"Inherent" SD right in CIL includes attacks by "irregulars"

* UNSC Resolution 1368 (2001): post 9/11 terrorist attacks

*Reaffirmed "inherent right"

Temporal scope: anticipatory self-defense? Preemptive SD?

* UN Charter (Art. 51): no explicit anticipatory right- only after an attack has occurred

* But in CIL: preemptive SD allowed in case of a manifestly imminent" attack

* Caroline incident (1837)- must meet necessity on account of "imminence" (US SecState Webster)

* ICJ: has strategically avoided ruling on whether an armed attack must occur

*e.g. Nicaragua, Armed Activities

vs.

Preventive SD= unlawful

* No legal justifications in IL for "preventive" war (against future, speculative threats

e.g. Pearl Harbor (Japan, 1941), Iraq (US, 2003)- widely viewed as illegal (aggression)

Legal authority

* Primary responsibility for maintaining int'l peace and security (Art. 24 (1))

* Can enforce the peace via diplomatic, economic, and military action

* May issu legally binding decisions ("shall decide") (+ non-binding "reccomendations")

Binding nature of UNSC decisions

* UN members agree to accept and carry out UNSC decisions (Art. 25)

* Unusually powerful

*Binding absent state consent

* Can intervene in "domestic" affairs or override states' other legal rights

* Lockerbie (1992): ICJ upheld UNSC sanctions despite Libya's right to not extradite its nationals to the UK/US

UNSC: members and voting

Members (15):

5 permanent members (France, People's Republic of China (pre-1971: ROC, Russia (pre-1991: Russia), United Kingdom, United States))

Vote: 9 affirmations (+ no veto), Unusual-- legally unequal status of P5 vs. others. Sovereign equality--- but other states consented when joining UN

10 elected members (6 before 1965): Elected for 2 years by UNGA (Africa: 3, Asia-Pacific: 2, Latin America: 2, Eastern Europe: 1, Western Europe and others: 2), 2025-26 (Denmark, Greece, Pakistan, Panama, Somalia), 2024-25 (Austria, Portugal, T&T, Kyrgz., Zimb.