The use of force: the legality of war as a tool of policy before and after the UN Charter

Aims

This course aims to:

• introduce you to the contemporary law governing the use of force in international relations and allow you to assess whether collective security works
   
• enable you to understand the (largely unsuccessful) attempts to limit the use of force prior to 
  World War II
   
• describe the change that came from the adoption of the UN Charter
   
• look at the contemporary world and consider what (if any) impact banning the use of force has had on today’s conflicts, with a particular emphasis on the Russian invasion of Ukraine

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. 

Yet in October 1945 human history changed profoundly with the adoption of the UN Charter. By outlawing the acquisition of territory by force, the Charter made aggressive war illegal, and in the process, sounded the end of the European territorial empires that had dominated much of the world from the 17th century onwards. Indeed, the UN’s membership increased from 51 in 1945 to 154 by 1980 directly as the result of the dissolution of the European empires. 

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.

Presentation of the course

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

Course sessions

1. The World before 1945 
   We begin in the world of the European empires, the attempts to create bloc-based deterrence before World War I and collective security measures in the interwar period, before considering why these (largely well-meaning) attempts failed, and what lessons they provided for the framers of the UN Charter. 
    
2. The UN Charter and the use of force 
   The ban on the use of force needs to be considered within the very particular circumstances of its formulation in 1945. We will consider what the trade-offs were, notably around the Security Council’s remit and the role of the veto. We will look in detail at the prohibition on the use of force, and through the judgements of the International Court of Justice, how the law has developed since 1945. 
    
3. Possible exceptions to the UN Charter regime 
   The previous session sets out the near-total ban on the use of force under the UN Charter. Since 1945, three-and-a-half exceptions have been proposed: the 1950 Uniting for Peace Resolution, the 1951 Genocide Convention, and the 2005 Responsibility to Protect (R2P), along with the half – the (mis)use of Article 51 (Self-Defence). Have any of these fundamentally changed the regime or reduced conflict?
    
4. Post–Cold War collective security: success or failure? 
   Collective security – the key tool to enforce the Charter’s prohibition on the use of force – was hamstrung by the Cold War’s polarisation which rendered much of the UN architecture inoperable. With the end of the Cold War, the UN Charter regime was able to operate much more as intended. How did it do? We will consider the 1990-91 Iraqi invasion, the 1994 Rwandan genocide, 1999 Kosovo war, the 2001 conflict in Afghanistan, the 2003 Iraq war and the Russian interventions in Ukraine from 2014 onwards. 
    
5. The future: Ukraine, Israel–Palestine and the future of the use of force 
   Taking the lessons of the post-Cold War period in Session 4, this session will look at what answers the international community has considered and why there is, as yet no agreement on the use of force outside the narrow confines of the UN Charter through the lenses of the Ukraine war and the war in Israel–Palestine after the HAMAS attack of 7 October 2023. 

Learning outcomes

You are expected to gain from this series of classroom sessions a greater understanding of the subject and of the core issues and arguments central to the course. 

The learning outcomes for this course are:

• to become familiar with contemporary international law governing the use of force
   
• to assess whether a State’s use of force is legal or illegal
   
• to understand the current debate on the use of force (e.g., by non-state actors, cyber-attacks) and their integration into the legal order

Required reading

Please note students are required to read either Henderson or Gray. Make sure that you have the latest edition – the case law is evolving, and it is important to have the most recent one.

*Gray, Christine D, International Law and the Use of Force (Oxford: Oxford University Press 2018, 5th edition) ISBN: 9780198808428, Chapters: 1, 4, 6, 7

*Henderson, Christine, The Use of Force and International Law (Cambridge: Cambridge University Press 2018) ISBN 9781107692008, Chapters: 1 (pp. 7-35), 2 (pp. 50-68), 3 (pp. 83-121), 6 (pp. 203-272), 7 (pp. 291-306), 10 (pp. 379-407)

Please familiarise yourself with the UN Charter:

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

*Uniting for Peace Resolution (UNGA Res 377A/B/C (V)): see Christian Tomuschat’s article: https://legal.un.org/avl/pdf/ha/ufp/ufp_e.pdf and the Resolution itself: https://www.un.org/en/sc/repertoire/otherdocs/GAres377A(v).pdf 

*R2P – see paras 138 and 139 of the 2005 World Summit Conclusions: https://www.globalr2p.org/resources/2005-world-summit-outcome-a-60-l-1/ 

*Kress, Claus, ‘On the Principle of Non-Use of Force in Current International Law’, https://www.justsecurity.org/66372/on-the-principle-of-non-use-of-force-in-current-international-law/ (30 September 2019)

Cases:

‘Armed Activities on the Territory of the Congo’ (Democratic Republic of the Congo v Uganda), Judgment, [2005] ICJ Rep 168: 116-20051219-JUD-01-00-EN.pdf (icj-cij.org)

‘Military and Paramilitary Activities in and against Nicaragua’ (Nicaragua v. United States of America), Merits, Judgment, [1986] ICJ Reports 14: 070-19841126-JUD-01-00-EN.pdf (icj-cij.org)

Typical week: Monday to Friday 

Courses run from Monday to Friday. For each week of study, you select a morning (Am) course and an afternoon (Pm) course. The maximum class size is 25 students.   

Courses are complemented by a series of daily plenary lectures, exploring new ideas in a wide range of disciplines. To add to your learning experience, we are also planning additional evening talks and events. 

Evaluation and Academic Credit  

If you are seeking to enhance your own study experience, or earn academic credit from your Cambridge Summer Programme studies at your home institution, you can submit written work for assessment for one or more of your courses.  

Essay questions are set and assessed against the University of Cambridge standard by your Course Director, a list of essay questions can be found in the Course Materials. Essays are submitted two weeks after the end of each course, so those studying for multiple weeks need to plan their time accordingly. There is an evaluation fee of £75 per essay. 

For more information about writing essays see Evaluation and Academic Credit. 

Certificate of attendance 

A certificate of attendance will be sent to you electronically after the programme.