In Determining Customary International Law: The ICJ’s Methodology between Induction, Deduction and Assertion, Stefan Talmon revisits the old debate over inductive and deductive methods for finding customary international law (CIL) to see whether we can now, fifty years after the original debates, learn any lessons about whether, when, and how the International Court of Justice uses each. What Talmon finds is that there are no clear patterns in how the ICJ uses each method, and that in fact, it is a third method, assertion, that best exemplifies the Court’s approach. What Talmon only hints at though are much broader lessons—that the ICJ’s failure to adopt a clear methodology for finding customary international law is only a symptom of a much broader problem, that the ICJ has never articulated a clear, coherent explanation of its authority to interpret customary international law or for whom. The ICJ’s efforts to find customary international law may simply be incoherent, a mirage, or even impossible.
The questions that Talmon’s study begs are why. Why isn’t the ICJ more interested in developing a clear methodology and why are there no patterns in the ICJ’s use of deductive or inductive methods? And why aren’t states more concerned? Why haven’t states demanded a clear methodology before treating ICJ decisions on custom as authoritative?
Methodology as Justification
Starting with the first question, the lack of clear methodology hints that the ICJ’s choice of induction, deduction, or assertion has little to do with methodology and everything to do with justification. When the Court invokes each one, it is attempting to justify its authority to interpret or find rules of CIL. Assertion makes this clearest—in the absence of any real evidence of a customary rule, the Court justifies it rules with appeals to “obviousness.” As Talmon wisely observes, both inductive and deductive methods are claims of derivative authority—the Court is not “making” or “choosing” a rule, but merely “finding” the rule made by states themselves in their interaction with one another. This is true whether the Court counts practice and weighs opinio juris or attempts to deduce a specific rule from recognized more general ones. It also tracks the requirement of article 38 of the ICJ Statute that the Court apply “international custom, as evidence of general practice accepted as law.” In essence, the Court‘s claim is that it is simply stepping into the shoes of states and making the same judgment they would make about specific rules and actions.
Negotiated Law and Adjudicated Law
The problem reflected in the ICJ’s methodological muddle is that this task may be impossible and the justification something of a fib. A court cannot step into a state’s shoes. A court forced to find a rule to decide a case is engaged in a fundamentally different activity than a state discerning a rule to guide its actions or jockeying for its favoured interpretation in relations with other states. Read the rest of this entry…