New York University Public Law and Legal Theory Working Papers

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Duke Journal of Comparative & International Law, Vol. 21, 2010


Duke law professors Curtis Bradley and Mitu Gulati (B&G) have written a very interesting, original paper questioning the conventional view of the binding effect of customary international law (CIL) - that once a customary rule becomes law by the dint of the widespread practice of states in the belief they are legally required to do so (termed opinio juris) it is binding on all states, with the possible exception of those who persistently objected to the rule during its formative stages. B&G maintain this “Mandatory View” of CIL is an ill-conceived twentieth century alteration of a previously established “Default View” of CIL that would allow states to withdraw from customary rules to which they object even if their objections are voiced after the rule has acquired the status of customary law. As they see it, the Default View does a better job of accommodating legal change than does the conventional position.

CIL is a profoundly stable institution, not because it has been able to address the serious analytical challenges academics and others have leveled but because of the advantages it provides its principal players: states (including their personnel and lawyers), international tribunals, and publicists/ academics. Most often interstate disputes are resolved by might called be called the application of prudence or comity; there is normally little point in acting unreasonably with respect to other states if you will need those states to recognize your similar claims. After a settled practice has emerged, publicists or the International Law Commission then may attempt a formal recitation of the practice. This strong dimension of reciprocity explains the development of, say, diplomatic immunity law and customary rules on the recognition of foreign judgments in domestic tribunals. For other matters, either the prospect of reciprocity may be less important or changes in relative power or stage of development among states may provoke change in customary practices. For such disputes, CIL provides a currency for negotiating differences that avoids language of self-interest, does not require use of force, and does not bind anyone, unless states have agreed by ex ante or post clause to refer the dispute to the International Court of Justice (ICJ) or other arbitral mechanism. For weak states - i.e., those that lack the means to use self-help measures to enforce their expectations of appropriate behavior by other states, such as seizure of fishing boats nearing waters they claim - CIL provides a means of saving face and registering objections short of force. For strong states - i.e., those that can use self-help - CIL provides a means of signaling the intensity of their claim initially without declaring resort to self-help or other force.

For these and other reasons developed in the paper, in the end, the system is better off with vigilant insistence on the conventional requirements for CIL formation - widespread practice and opinion juris - and the conventional consequences for the formation of customary rules - you are bound until by your practice and the practice of other states the customary rule gives way to a new custom.

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