Theories of compliance with international law

More than three decades ago, Louis Henkin asserted that "almost all nations observe almost all of their obligations almost all of the time". Since there is no coercive power in the international system comparable to that which enforces the laws of a state, however, the question what motivates states to comply with international law remains among the most perplexing ones in international relations. In national legal systems, there are various rules establishing the authority of courts of law to adjudicate disputes arising members of the community. While this is the rule, disputes may also be settled by way of arbitration whereby disputes on civil or commercial matters can be decided by a third party chosen by the litigants. At the international level, however, such enforcement mechanisms are only rudimentarily developed. Indeed, until the adoption of the United Nations (UN) Charter in 1945, states were authorized to resort to force to impose their terms of settlement, unless they had entered into treaties requiring self-restraint on the matter. Thus, states were authorized to enforce their rights militarily without resorting to any sort of peaceful settlement. Even though states induced compliance with international rules considerably by way of strength ening institutional dispute settlement mechanisms as well as by preventing disputes, the enforcement mechanisms still happen to be rudimentary compared to those in developed national systems. Given this lack of highly developed enforcement mech anisms, the question why states should or indeed do comply with international norms has to be addressed.

At first sight, contemporary philosophy of international normativity tends to appear as a fully developed theory intended to explain the dynamics of national legal phe nomena. Granted, some basic notions seem applicable to an understanding of the nature, purposes, and workings of the international arena. Notions of basic human rights, limits on authority, distributive justice, and so forth developed in one society or culture, may have global application, but the transfer must be justified and its rationale cannot be simply assumed. If Macchiavelli is right that the requisites for owder are "good laws and good arms. [but] there cannot be good laws where there are not good arms", the prospect for compliance with international law seems to be rather remote. However, most contemporary legal philosophers deem coercive power necessary but insufficient to secure habitual social assent to governance. Contrary to the Macchiavellian notion, these theorists rather focus on authority as a process iden tifying in necessary or desirable characteristics, such as consent, openness, and par ticipation. If therefore this line of inquiry holds true, opening to consider non-coercive factors in understanding the phenomenon of norm compliance, the prospect of com pliance is considerably better than in a situation where there are not good arms'.

Looking closer, it shows that since Henkin's statement empirical work seems largely to have confirmed this hedged, but optimistic description. Nevertheless, scholars have generally avoided the causal question 'why states obey international law. This failure to deal with the question of compliance is troubling because compliance is one of the most central questions in international law. Indeed, the very absence of an explana tion for why states and other subjects of international law in some cases obey inter national law and do not do so in other cases threatens to undermine the foundations of the international legal system. In case international law matters, it has to influence in some way or other the actors' behavior. Without an understanding of the con nection of law and behavior, an explanation for the very function of the international legal system is missing. We therefore remain ill-equipped to predict or explain the real impact of the over 50,000 international agreements now in force.