ABSTRACT
The sources of law are commonly classified as "formal" and "material". Side by side with these there are the "evidences" or records of law. It is often said, and sometimes simply assumed that in the international field, treaties, and international agreements generally, are the equivalent of the domestic law statute, or at least a substitute for it, and serve a substantially similar purpose. The rule pacta sunt servanda is not the only rule of this kind in the international field. In the field of domestic, as opposed to international law, this may well be the case, although the reason for its being so may rather be that there is not the same occasion for underlying differences to find open expression. The formal sources of obligation must be distinguished from the formal sources of law. They may coincide, but may not, and are in any case distinct concepts.
