Using a classical perspective tending to interpret existing positive international law, this chapter pursues a double objective. First, it fits in with the doctrinal trend embodied by the Institut de droit international (IDI) in emphasising that intervention by invitation is unlawful if it implies interference in an internal situation, contrary to the right of peoples to self-determination. Second, this research highlights the growing role of the UN Security Council in appraising and characterising the conditions surrounding the legal validity of intervention by invitation. The chapter focuses on military operations in Mali (2013), Iraq (2014), Syria (2015), Yemen (2015), and The Gambia (2017). It observes how, by adopting resolutions, the UN Security Council made pronouncements on which authority was entitled to give its consent, and on the legitimacy of the object and effects of the intervention. The chapter concludes that the Council no longer necessarily authorises any military intervention, but centralises and multilateralises the appraisal of the circumstances surrounding the formulation of the invitation.

There is nothing surprising in this, remembering that the very objective of this statement of the principles already contained in Article 2 of the UN Charter is ‘to secure their more effective application within the international community’. This was a particularly topical issue in 1970 with respect to the prohibition of the use of force. It can hardly be said that this prohibition was uniformly and systematically applied after being solemnly proclaimed in the Charter in 1945. The stringency of the prohibition, presented by many as a major advance in international relations, was soon confronted with the harsh realities of practice: besides major conflicts such as the Korean War (1950–53), the Arab–Israeli wars (especially the Six-Day War in 1967) or the Indochina and then Vietnam war (which was still being waged), the United Nations had already experienced multiple flash points by 1970, from the Cuban missile crisis (1962) to the Soviet interventions in Hungary (1956) and Czechoslovakia (1967), by way of US military operations in Cuba (1961) and the Dominican Republic (1965), and the Suez crisis (1956), not counting the colonial or post-colonial conflicts (such as the Belgian intervention in the Congo in 1960) or other local conflicts. Against this backdrop, it is understandable that, if they were to continue on an idealistic or even utopian course, the UN Member States might as well see the reaffirmation of the outline definition of the prohibition of the use of force as a way to make it more effective. The solemn proclamation of the existence of the rule, which was set out at the time as a peremptory norm of international law (jus cogens), thus appeared to be a way to curb the reign of force that it seemed was to characterise international relations.

Developments in current international law have raised the perception of gaps in the field of secession. It seems that States constantly oscillate between two tendencies. The first is characterised by the refusal to extend international legal regulation (apart from that applicable to protecting human rights) to what is a priori a matter of State sovereignty and ‘internal affairs’. It does not appear therefore to be a question of a lacuna, this term implying that the law does not give an answer to a question that arises in its field of application, this last condition not having been filled.

The second tendency consists of opposing to secessionist groups and their sources of external support the obligation to respect the territorial integrity of the threatened State and, in parallel, legalising the principle of military response of the latter. Then, far from being neutral or silent on the matter, international law seems to rule very clearly in favour of the State.

LE DROIT INTERNATIONAL EST-IL LACUNAIRE SUR LA QUESTION DE LA SÉCESSION?

On a généralement défini la sécession comme ‘la démarche par laquelle un groupe ou une partie d'un Etat cherche à se détacher de l'autorité politique et constitutionnelle de cet Etat, en vue de former un nouvel Etat doté d'une assise territoriale et reconnu au niveau international’. Pour notre part, nous envisagerons plus spécifiquement la sécession comme la tentative de créer un Etat par la force ou la violence, en ne retenant pas les hypothèses de création d'Etat opérées par la voie pacifique que l'on qualifiera de séparation voire, si l'Etat prédécesseur a cessé d'exister, de dissolution.