Contemporary War: can law regulate the use of force?

Aims

This course aims to:

• introduce you to the law governing the use of force in international relations and allow you to assess the lawfulness of today’s conflicts
• enable you to understand the (largely unsuccessful) attempts to limit the use of force prior to World War II and describe the change that came from the adoption of the UN Charter
• introduce the law of armed conflict and how this is applied in contemporary wars

Course content

Carl von Clausewitz stated that 'War is the continuation of politics by other means', offering a clear understanding of why world history is punctuated by wars of conquest. Wars create, divide and destroy empires, built walls, roads and bridges, dammed rivers, and changed the very essence of our natural world. Empire-by-conquest was a universal, global, phenomenon that punctuated the ages. 

But if the use of force as state policy was largely unrestricted before the 1920s, societies globally have long limited the manner in which force can be used: refusal to take surrenders or attacking civilians has long been contrary to societal norms in civilisations around the world. In understanding the use of force in the round, we need to understand what the limits on the manner in which force is used. 

In October 1945 human history changed profoundly with the adoption of the UN Charter which made aggressive war illegal. However, if you were a visitor from Mars, you would be right to be confused: war seems to be used much as Clausewitz held. The University of Michigan’s Correlates of War lists 144 inter-state wars between 1945 and 2007, a total that has been consistently added to in the years since, suggesting that the Charter’s ban on the use of force is at best marginally relevant, or at worst has failed. 

This course argues that despite these conflicts, collective security premised on the Charter’s ban on force remains the cornerstone of contemporary international relations, illustrated by the pseudo-legal arguments’ aggressors use to buttress their claims. This course examines the UN Charter and International Court of Justice jurisprudence and identifies where and how the law is developing. 

What to expect on this course

This course will take the form of ten 90-minute lectures with slides and additional reading. 

Course sessions

1. What is law’s role in regulating force?: This introductory lecture explains the different but complimentary sets of rules that govern the use of force. These comprise the law governing whether the use of force is legal (jus ad bellum) and whether the manner that hostilities were conducted is legal (jus in bello)

    

2. UN Charter regime in Theory: Between 1945 and 2000, more than 41 million people died in conflicts. In the 25 years since, we have seen major wars in Congo/Great Lakes, Afghanistan, Iraq, Syria, Yemen, Ukraine, Israel/Palestine and insurgencies around the world. Through considering state practice, the judgements of the International Court of Justice and evolving norms, this lecture examines how the UN system is designed to work based on the Charter’s design. This includes how the UN Charter authorises force, what is and is not self-defence, and what is the legal test for the pre-emptive use of force. 

    

3. UN Charter regime in Practice: In contrast to the theory, this looks at how the system works in practice after the adoption of the Charter, including changing Security Council membership over time, how the Security Council works, and what is the veto. It finishes with case studies for UN authorisation, pre-emptive use of force and preventative use of force.

    

4. Contemporary Law of Armed Conflict (LOAC / IHL): This charts the regulation of war from its earliest days through the Middle Ages to today. We will see that there is a breadth of international practice and similar laws in very different cultural and historical contexts, coming together in the creation of the International Committee of the Red Cross (ICRC) under Henri Dunant, and the 1949 Geneva Conventions incorporating the lessons of World War II.

    

5. Ending Impunity: For most of human history, victims of war crimes and crimes against humanity had no real prospect of holding perpetrators to account. This lecture begins with the International Military Tribunals (IMT) at Nuremburg and Tokyo after World War II and then moves to the International Criminal Tribunals for Rwanda and Former Yugoslavia (ICTR/ICTY), before looking at today’s International Criminal Court (ICC).

    

6. Using Law to limit force: Efforts to ban specific types of weapons began in earnest in the second half of the 19th century. This gathered pace in the 20th century, and the control and then the reduction in nuclear weapons became a centrepiece of Cold War and post-Cold War diplomacy. This lecture uses nuclear weapons controls as a case study and as a salutary lesson before considering the specific regimes for chemical, biological and specific types of conventional weapons. 

    

7. The supreme international crimes: aggression and genocide 
   IMT Nuremburg defined aggression as the ‘supreme international crime’, as it was the action that then resulted in all of the crimes that followed, including the newly defined crime of ‘genocide’. This lecture looks at aggression and genocide specifically, and plots the differing routes for accountability that each crime has taken.

    

8. Case Study I: Ukraine 2014 – Present: Russia’s intervention in eastern Ukraine’s Donbass region began in 2014, escalating to a full-scale invasion in 2022, creating Europe’s largest conflict since 1945. We will look at the legal origins of the conflict, the actions and reactions of other international players and the ICC, as well as the creation of the Special Tribunal for the Crime of Aggression. 
   
    

9. Case Study II: Two wars with Iran, 2025-26: 2025 and 2026 have seen conflicts between the United States and Israel on one side and Iran on the other. What legal claims were made by each actor, and how solid are they? What mechanisms exist for accountability, and how realistic are they? 

    

10. Law’s Limits and the Future: This lecture will look at what happens when the Security Council is confronted by atrocity and is unable or unwilling to come to a consensus on how to act. What are the options? Do the current assaults on the international legal order make it meaningless. What does the future hold? 

Learning outcome

As a result of the course, you will gain a greater understanding of the subject and you should be able to:

• become familiar with contemporary international law governing the use of force (both jus in bello and jus ad bellum)
• assess whether a State’s use of force is legal or illegal, and if force is used, whether it is used legally or illegally
• understand the current debate on the use of force (eg. by non-state actors, cyber-attacks) and their integration into the legal order

Required reading

UN Charter, https://www.un.org/en/about-us/un-charter/full-text 

The only required reading for the course is the Preamble to the UN Charter. The course will be completely comprehensible to the non-specialist without additional reading. 

However, if you are taking the course for credit, or are intending to go further in the subject, there will be specific readings tailored to the lectures which will be available on the VLE once registered.