Since Grotius' De Jure Belli ac Pacis, the architecture of the international legal system has been founded upon a distinction between the states of war and peace. At the beginning of the 20th century, it was taken for granted that "the law recognizes a state of peace and a state of war, but that it knows nothing of an intermediate state which is neither one thing nor the other." (1) Today, this claim stands to be revisited.
There are strong indications that the contemporary architecture of international law is growing out of the bipolar "peace" and "war" distinction and developing into a tridimensional system, covering the phases of conflict, peacetime relations and the transition from conflict to peace. International practice has dealt with multiple situations which are neither "declared wars" in the conventional sense, nor part of peacetime relations, such as threats to peace caused by repressive state policies. Moreover, international law comes into play in processes of transition from one stage to the other, namely in transitions from "peace" to "war" or in transitions from "war" to "peace."
This transformation is not reflected in the contemporary conception of the law of armed force. This body of law continues to be based on a dualist conception of armed force which distinguishes the law of the recourse to force (jus ad bellum) from the law governing the conduct of hostilities (jus in bello).
This dualist conception of the law of armed force appears to carry an idea of exclusiveness that is increasingly anachronistic. It fails to reflect the growing interrelation between armed violence and restoration of peace and the growing impact of international law on the restoration of peace after conflict.
Developments in modern peacemaking suggest, in fact, the emergence of a third body of norms that complement the traditional dualist concept and which can be referred to as "law alter conflict" or "jus post bellum.'' (2)
The idea of a tripartite conception of the law of armed force is not entirely new. Calls for an expanded conception of armed force were already made by proponents of the "just war" doctrine. Francisco Suarez, for example, argued in favor of extending the just war categories to a third period, namely the ending of justly declared and fought wars. (3) This thinking was later developed by Immanuel Kant, who introduced the notion of "right after war" (Recht nach dem Krieg) in his philosophy of law (Science of Right), which formed...