Although, as has been stated, no single nation can establish any principle of international law, still systems of private law are often resorted to, to aid in the solution of questions of international law. This is particularly true of the great system of Roman law.

14 Thirty Hogsheads Sugar vs. Boyle, 9 Cranch, 198.

"As it was the only system of law with which the earlier writers on international law were familiar, and as its principles seemed to be sufficiently general, in character and scope, to apply to the reciprocal relations of states, its authority was frequently invoked by them in the preparation of their treatises." 15

As various portions of the system of international law are constantly administered in the regular courts of the different nations, the decisions in such cases constitute an important source of authority on such portions of international law. That international law is part of the law of the United States has been repeatedly decided by the Supreme Court of the United States.

"International law, in its widest and most comprehensive sense - including not only questions of right between nations, governed by what has been appropriately called the law of nations, but also questions arising under what is usually called private international law, or the conflict of laws, and concerning the rights of persons within the territory and dominion of one nation, by reason of acts, private or public, done within the dominions of another nation - is part of our law, and must be ascertained and administered by the courts of justice, as often as such questions are presented in litigation between man and man, duly submitted to their determination." 16

"The laws which the citizens of the United States are to obey in regard to intercourse with a nation or people with which they are at war are laws of the

United States. These laws will be unwritten international law, if nothing be adopted or announced to the contrary; or the express regulations of the government when it sees fit to make them. But in both cases it is the law of the United States for the time being, whether written or unwritten." 17

15 Davis on International Law, page 20.

16 Hilton vs. Guyot, 159 U. S., 163.