If then there is no common superior which can prescribe principles of international law, and such principles cannot be prescribed by an individual nation, what are the sources from which the principles of this branch of the law have arisen?

The answer to this question must be in the form of an enumeration rather than a definition, and it must be remembered that wherever a rule of international law may originate, it only becomes binding by the force of custom and through general acquiescence.

The following enumeration of the sources of international law has been given by a United States official,13 in his recent work on this subject:

The Roman Law.

The Jus Gentium.

Custom and Usage.

Treaties and Conventions.

The Municipal Law of States.

The Judgments of International Courts, or Boards of Arbitration.

The Decisions of Municipal Courts upon Questions of International Law.

13 See "The Elements of International Law, with an Account of its Origin, Sources, and Historical Development," by George B. Davis, Lieut. Col., and Deputy-Advocate Gen. U. S. A., Professor of Law at the United States Military Academy (1900).

The Diplomatic Correspondence of States, State Papers, Foreign Relations, etc.

General Histories; The Histories of Important Epochs; Biographies of Eminent Statesmen.

The Works of Text Writers.

International Public Opinion.

The Supreme Court of the United States has said on this point:

"The law of nations is the great source from which we derive those rules, respecting belligerent and neutral rights, which are recognized by all civilized and commercial states throughout Europe and America. This law is in part unwritten, and in part conventional. To ascertain that which is unwritten, we resort to the great principles of reason and justice; but, as these principles will be differently understood by different nations under different circumstances, we consider them as being, in some degree, fixed and rendered stable by a series of judicial decisions. The decisions of the courts of every country, so far as they are founded upon a law common to every country, will be received, not as authority, but with respect. The decisions of the courts of every country show how the law of nations, in the given case, is understood in that country, and will be considered in adopting the rule which is to prevail in this." 14

Some of the more important of these sources of international law will be discussed separately in the succeeding sections.