What are the sources of public international law?
If by source we mean its beginning as law clothed with all the authority required to give it binding force, then there is but one source, and that is the consent of nation: presumed, in case of the general law; tacit, in case of the customary law; and express, in case of the conventional law of nation.
If, on the other hand, we take the sources of international law to be the place where its rules law are: (1) customs and usages; (2) treaties and other interstate agreements; (3) decision of international tribunals; (4) decisions of national tribunals, such prize courts; (5) works of jurists and commentators; (6) diplomatic papers; (7) unilateral acts or laws, ordinances, proclamation, etc. issued by states; (8)opinions of statesmen; (9) the law of nature.
[Note: Historians generally use the term "evidences" for "sources." Accordingly, the evidence of international law are: (1) customs and usages; (2) treaties and other interstate agreements; (3) decisions of international tribunals; (4) decisions of national tribunals; ?(5) works of jurists and commentators; (6) diplomatic papers; (7) unilateral acts or laws, ordinances, proclamations, etc. issued by states; (8) opinions of statesmen; (9) the law of nature.]
(1) Customs and usages.__To constitute rules of international law, customs and usages must be more or less universal, tacitly accepted as binding upon states with the force of law. At first they might have been of limited effect, being positive prescriptions of one or more states; but in the course of time because of their reasonableness and utility, and of their being just, they have been acquiesced in and accepted as of general obligation. The Rhodian Law, supposed to have been the oldest system of martime rules, was a code for Rhodians only; but because it was later accepted and assented to as wise and desirable system by other maritime nations, it became of general authority. The same was true of the Amalphitan Table, of the ordinances of Louis XIV, all of which became the law of the sea not because of their origin but by reason of their acceptance as such.
