BUL Event on the Use of Force, Legitimacy, Non-state Actors, and Bilateral Security Agreements


| Jan 30, 2023

Use of force

On January 18, at the Brunel University London (BUL) School of Law, the BUL International Law Group, held an event exploring the use of force and international law (the video can be found here). The discussants addressed questions that are sure to be on the minds of international law researchers in the near future and it is on this account that I want to offer my own as well. With a major conflict ongoing between Russia and Ukraine and several others around the world, the event put in its kaleidoscope three themes related to the use of force: legitimacy, non-state actors and bilateral intervention agreements.


On this account, Dr. Christoforos Ioannidis, King’s College London Dickson Poon School of Law, explained under which circumstances legitimacy can become an objective standard that can be used to justify the use of force. Bemoaning how the legitimacy card has been used so far in the cases of Kosovo or the second Iraq War, Dr. Ioannidis advocated a clear threshold and necessary conditions like democracy or retention of human rights in order for any use of force to be able to be termed “legitimate,” attributing also a moral parameter to the use of force. His point raises the question of whether legitimacy can be used in principle as an ex ante notion or as Dr. Yahli Shereshevsky, Senior Lecturer at the University of Haifa Faculty of Law later noted, legitimacy is always a notion that is brought ex post.

Retaining the possibility for legitimacy to be brought also ex ante, Dr. Ioannidis underlined the independent identity of legitimacy as a notion vis à vis legality, with Dr. Pietro Sullo, Reader at the Brunel University London School of Law, asking whether this should mean that legitimacy will replace legality as a ground for military intervention in the future.

The question is cardinal and lies at the core of whether international law in general and the use of force in particular, should be seen on a de lege lata or de lege ferenda basis. International practice regarding the right to self-defense has demonstrated that when it comes to the notion of the use of force, a de lege ferenda reading cannot be automatically excluded. Thus, whereas on a de lega lata basis, Article 51 of the UN Charter holds that the right to self-defense can be exercised only against States, self-defense also against non-State actors has been asserted by scholars on a de lege ferenda basis, following 9/11.

Non-State Actors

The second idea considered was the position taken by Dr. Shereshevsky regarding the fact that the use of force against non-State actors should be equally deemed in violation of international law in the way this is true regarding the use of force against States. Underlining how States exercising force even against non-State actors refer to the notion of self-defense as a justification, Dr. Shereshevsky detected that States do consider that the use of force against non-State actors can be illegal and thus seek to justify it. This equation of State and non-State actors when it comes to the exercise of armed force, is interesting and can be added to the general framework regarding the equation between the two different entities also in a number of other issues, such as their binding by international human rights law or international humanitarian law standards.

Bilateral Security Agreements

Finally, a third parameter concerned bilateral security agreements between States giving them the right to militarily intervene in one other’s territory. Dr. Saeed Bagheri, Lecturer at the University of Reading School of Law, underlined dangers lurking behind some arrangements that employ terse or vague wording left to broad interpretation. He argued that State consent for another State to invade the first’s territory can never be valid. On this, the question is why. If respect for sovereignty is the dictating factor behind forbidding consent to foreign intervention, consent in the first place can be deemed an exercise of sovereignty assuming the consent has been given freely and according to the State’s internal constitutional processes.

When this is not so, the legitimacy argument previously addressed by the discussants must be reconsidered. It is true that military agreements can be prone to abuse by invading States, either in loco or in tempo, with the State intervening more than required in foreign territory or conducting operations without coordination or warning. Yet, any such violations raise the question of whether they are so grave as to create a threshold that, a priori, disqualifies the conclusion of such agreements. The point returned the discussants to the legitimacy discussion and the need for a threshold there closing the discussion and lending to a circular aspect.

Concluding Thoughts and Thanks

In conclusion, the event brought to the table new ideas and approaches to the way future discussions on the use of force should be shaped. The BUL International Law Group thanks discussants for their contributions. They also serve as a turning point for the future events the Group is organizing and have been highly enlightening in light also of the current Ukraine-Russia conflict.


Dr Solon Solomon is Lecturer (Assistant Professor) in the Division of Public & International Law at Brunel University London, School of Law and co-Director of the BUL International Law Group.


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