Can the Use of Force Be “Lawful” in War? The international humanitarian law Perspective

Throughout the course of history, that the use of force has been proven in causing destruction, and death which ultimately threaten the world’s peace and security. Article 2(4) of the United Nations Charter (UN Charter) has laid down the general prohibition on the threat or use of force which now have been accepted as a jus cogens norms by the international community [1]. The international humanitarian law (IHL) has also provided exceptions to the prohibition of use of force.

The most well-known exception is the right to self-defence which is enshrined in Article 51 of the UN Charter. The primary aim of this right is to deter aggression and to protect the integrity and territorial sovereignty of the State. It is a defensive right rather than retributive [2]. Prior to the UN Charter, the enforcement of this right was subjected to the conditions of necessity and proportionality which arguably establish the right to ‘anticipatory self-defence’ of State. However, UN Charter later established that self-defence must be in response to an actual armed attack. This is been supported by the International Court of Justice (ICJ) in the case of Nicaragua v The United States of America [3]. Another circumstance that justifies the use of force under IHL under the UN Collective Security System. There must be unanimity among the Permanent Members of the UN Security Council in order to permit the use of force in response to an act of aggression or any threat to peace and security [4].

However, even when use of force is justified under IHL, it must be conducted in accordance with the principles of jus in bello. Jus in bello (literal meaning: the law in waging war) govern the conduct of hostilities and provides ground justifying the transition from peace to armed force [5]. Meanwhile, jus ad bellum (literal meaning: right to wage war) limit the consequences or armed conflicts on non-combatants (including vulnerable groups such as the wounded, women and children), property and the environment. Although the two concepts are different, they are closely related to each other since a violation of jus in bello might call into question the legality of using force. 

It is essential to note that adherence to both jus in bello and jus ad bellum is crucial to ensure the protection of civilians during armed conflict. As the International Committee of the Red Cross (ICRC) notes, "respect for the principles of distinction, proportionality, and precaution is essential to protecting civilians and civilian objects from the effects of hostilities, in accordance with international humanitarian law" [6]

Reference

[1] https://www.un.org/en/about-us/un-charter/full-text

[2] Mohammad Naqib Ishan Jan, Use of Force in International Law, p. 3

[3] Case Concerning Military and Paramilitary Activities in and against Nicaragua (Nicar. Vs. U.S.) (1986) ICJ Rep. 14

[4] Mohammad Naqib Ishan Jan, Use of Force in International Law, pp. 163-164

[5] Carsten Stahn, ‘Jus ad bellum’, ‘jus in bello’ . . . ‘jus post bellum’? – Rethinking the Conception of the Law of Armed Force’, The European Journal of International Law Vol. 17 no.5 © EJIL 2007

[6] International Committee of the Red Cross. (2016). What is international humanitarian law? Retrieved from https://www.icrc.org/en/what-is-iHL.

Prepared by, 

Noraini Roslie

31 December 2025