This spring, Florence was cluttered with peace flags, hanging out from private apartments, churches, official buildings, and businesses. One day in the middle of March, I counted as many as 50 bandiere de la pace in a single street crossing in the Oltrarno area, south of the river Arno. On 9 June 31 of them were still hanging there. At the time of my first count, it was obvious that the flags all meant “no” to the military action that was to begin in Iraq. What did they mean two months after the fall of Baghdad?

In two recent cases before the Court of Justice of the European Union (CJEU), the General Court (at first instance), the High Court of Justice of England and Wales and the Grand Chamber of the CJEU found that a trade agreement and a fisheries agreement between Morocco and the European Union cannot be applied to occupied Western Sahara without the consent of its people. In spite of the fact that it is the general view that Western Sahara is under belligerent occupation, none of the three courts invoked the law of occupation but based themselves instead on the principle of self-determination and the law governing the administration of non-self-governing territories, including the principle of permanent sovereignty over natural resources. A possible implication of these judgments is that that law and the law of occupation are converging in certain respects, in particular as regards long-term occupation. This pertains not only to the substantive rules on the exercise of authority, which seem to require that the people are heard, but also to the basis for the establishment of that authority, namely bare control.

What does authority mean under international law? There are various actors with different forms of authority, but no overarching concept of what characteristic endows an actor with authority, and even less of a coherent conception of legitimacy as a requirement for such authority. In fact, international law recognizes different authorities for different causes and different contexts, allocated to different actors, who base their authority on different characteristics (state legitimacy, representativity, military power, control). After disaggregating the concept of authority and outlining some of the consequences that follow from each type, this article highlights a number of different actors and describes the various authorities each has under international law. For instance, under jus in bello, nonstate actors can create a state of armed conflict in which they can often continue to use military means without legal sanction. While jus ad bellum may still in principle require legitimacy (in the formal sense of being a state), current jus in bello covers a range of non-state actors. Thus, from a practical point of view, the jus in bello regulations undermine any jus ad bellum requirement of legitimate authority.