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Customary International Law: Introduction to Evidence of Customary International Law

Introduction to Evidence of Customary International Law

The Restatement describes the evidence of international law in §103. Of particular interest to the researcher of custom is §103(2)(d) which describes the evidence of pronouncements of states:

§ 103 Evidence of International Law

(1) Whether a rule has become international law is determined by evidence appropriate to the particular source from which that rule is alleged to derive (§ 102).

(2) In determining whether a rule has become international law, substantial weight is accorded to

(a) judgments and opinions of international judicial and arbitral tribunals;

(b) judgments and opinions of national judicial tribunals;

(c) the writings of scholars;

(d) pronouncements by states that undertake to state a rule of international law, when such pronouncements are not seriously challenged by other states.