This article examines the status of military and civilian personnel of sending states and international organisations involved in UN peace operations. It undertakes an assessment of relevant customary law, examines various forms of treaty regulation and considers topics and procedures for effective settlement of open issues prior to the mission. The author stresses the need for cooperation between the host state, the sending states and the international organisation in this context. He draws some conclusions with a view to enhancing the legal protection of personnel involved in current and future UN peace operations.

Multifunctional peace operations have become an integral part of international society to the extent that they are now one of the major regulating institutions of international relations. The United Nations (UN) is the main player in setting up such operations. The UN has seen a major but gradual evolution of its role in maintaining and establishing peace. Having developed peacekeeping as a form of impartial interposition between belligerents during the Suez Crisis in 1956, the UN has continually broadened its sphere of action. These cumbersome and complex operations are demanding and present the UN with a number of challenges.

The multifaceted nature of peace operations today and the increasingly violent environments in which their personnel operate increase the likelihood of their being called upon to use force. It thus becomes all the more important to understand when and how international humanitarian law (IHL) applies to their action. This article attempts to clarify the conditions for IHL applicability to multinational forces, the extent to which this body of law applies to peace operations, the determination of the parties to a conflict involving a multinational peace operation and the classification of such conflict. Finally, it tackles the important question of the personal, temporal and geographical scope of IHL in peace operations.

The article aims to examine, in light of the codification work of the International Law Commission and of the most recent practice, some issues concerning the allocation of responsibility between an organisation and its troop-contributing states for the conduct taken in the course of a multinational operation (with a specific focus on UN operations). After explaining the general rule of attribution of conduct based on the status of the multinational force as an organ or an agent of the organisation, this article will examine the validity of special rules of attribution of conduct based on the notions of ‘effective control’ or ‘ultimate control’ over the acts of the multinational force. Finally, I will discuss the possibility of dual responsibility of both the organisation and the troop-contributing state concerned.

This article describes some of the challenges raised by multinational operations for the application of international humanitarian law. Such challenges are the result of different levels of ratification of treaties, divergent interpretations of shared obligations, and the fact that there is no central authority that determines who is a party to an armed conflict. The article discusses methods that have been developed to ensure ‘legal interoperability’. Some of these methods attempt to avoid situations where such interoperability is required. Where this is not possible, a ‘maximalist’ or a ‘minimalist’ approach can be taken, and in practice these are usually combined.