L10: The Use of Force

What fundamental principle governs the use of force in international law?

The prohibition of the use and threat of armed force, as established in the UN Charter and customary international law (ius contra bellum).

When was the prohibition on the use of armed force introduced?

After World War II, with the adoption of the UN Charter.

What are the three periods in the historical development of the law against war?

1. Just War (Bellum Iustum): Up to 1800, focused on moral justifications for war.

2. Ius ad Bellum: 1800-1914, recognizing the right of sovereign states to wage war.

3. Ius Contra Bellum: Post-1914, focusing on the absolute prohibition of war.

What are the key elements of St. Thomas Aquinas' concept of just war?

1. Public authority.

2. Just cause.

3. Pure intention.

What was the significance of the Kellogg-Briand Pact of 1928?

It condemned war as a tool of national policy and emphasized peaceful dispute resolution, marking a shift toward ius contra bellum.

What does Article 2.4 of the UN Charter state?

“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.”

How does the UN Charter institutionalize collective security?

Through the Security Council, which can impose sanctions or authorize military action to maintain or restore international peace and security (Articles 39-42).

What is the difference between ius ad bellum and ius in bello?

• Ius ad Bellum: Governs the legality of going to war.

• Ius in Bello: Governs conduct during armed conflict, focusing on humanitarian principles.

How are ius ad bellum and ius in bello applied independently?

The legality of the use of force (ius ad bellum) is assessed separately from the conduct of warfare (ius in bello).

What forms of force are covered by the prohibition in Article 2.4 of the UN Charter?

Armed force, including direct and indirect actions, but not economic, political, or psychological coercion.

Does the prohibition apply to internal conflicts?

No, it applies only to international relations between states.

What is the significance of the ICJ’s Nicaragua case (1986)?

It established that supporting armed groups in another state can amount to an indirect use of force, violating Article 2.4.

What are the two recognized exceptions to the prohibition on the use of force?

1. Self-Defense: Under Article 51 of the UN Charter.

2. UNSC Authorization: Under Chapter VII of the UN Charter.

What are the conditions for self-defense under international law?

1. Response to an armed attack.

2. Immediate action.

3. Proportionality.

4. Reporting to the Security Council.

How is an “armed attack” defined?

An act of physical force of significant scale and effects, such as an invasion or bombardment.

Can self-defense be invoked against non-state actors?

Yes, depending on the interpretation of Article 51:

1. Only if the actions are attributable to a state.

2. Broader views allow it against non-state actors directly.

What is anticipatory self-defense?

Military action taken to prevent an imminent armed attack.

Is preventive use of force legal under international law?

No, as it does not meet the criteria of immediacy, necessity, and proportionality.

What powers does the Security Council have under Chapter VII of the UN Charter?

To impose sanctions and authorize the use of armed force to address threats to peace.

Why has the UNSC’s collective security system not been fully implemented?

Member states have not provided the necessary armed forces, and the Military Staff Committee is inactive.

What are the controversial cases of unilateral use of force?

1. Protection of nationals abroad.

2. Intervention by invitation.

3. Defense of democracy.

4. Humanitarian intervention.

What is the Responsibility to Protect (R2P) doctrine?

States must protect their populations from human rights violations. If they fail, the international community, with UNSC approval, may intervene.

Is humanitarian intervention without UNSC authorization legal?

No, it is not recognized as an exception under customary international law.

What was the significance of the Caroline case (1837)?

It established the principles of necessity and proportionality in self-defense.

What precedent did the ICJ’s judgment in the Israeli-Palestinian Wall case (2004) set?

It reaffirmed that self-defense under Article 51 applies only to armed attacks by states.

What did the ICJ conclude in the Nicaragua case regarding customary law and the UN Charter?

Customary law operates parallel to the UN Charter and applies even if the Charter cannot be invoked.