Notably, the government never contested that it must abide by international law. Both parties in the case were invoking customary international law—the prevailing and long-running practices and norms that are observed and accepted by most countries as obligations—but differed as to what it permitted with respect to prizes. In a 6-3 decision authored by Justice Gray, the Supreme Court ruled that coastal fishing vessels are exempt from capture as prizes of war under customary international law, which, barring a "controlling executive or judicial decision," must be incorporated into the corpus of U.S. law. The Court cited lengthy legal precedents in support of this conclusion, which it described as an "ancient usage among civilized nations, beginning centuries ago, and gradually ripening into a rule of international law." In 1403, King Henry IV of England decreed his officers leave fisherman alone during times of war. He then signed a treaty with France reaffirming this act between both parties. Similarly, in 1521, a treaty between Emperor Charles V of the Holy Roman Empire and Francis I of France exempted fishing vessels from capture, on the basis that both nations would face widespread hunger if fishermen did not feel safe to set sail. Justice Gray also relied on the theories and opinions of contemporary jurists and commentators from across the world to buttress the Court's reasoning, decades before such scholarly legal work would be codified as a primary source of international law:[A]t the present day, by the general consent of the civilized nations of the world, and independently of any express treaty or other public act, it is an established rule of international law, founded on considerations of humanity. . . and of the mutual convenience of belligerent states, that coast fishing vessels, with their implements and supplies, cargoes and crews, unarmed and honestly pursuing their peaceful calling of catching and bringing in fresh fish, are exempt from capture as prize of war.Among the most oft-cited and famous quotes of the decision concerned the relationship of international law to domestic U.S. law:International law is part of our law, and must be ascertained and administered by the courts of justice of appropriate jurisdiction as often as questions of right depending upon it are duly presented for their determination. For this purpose, where there is no treaty and no controlling executive or legislative act or judicial decision, resort must be had to the customs and usages of civilized nations, and, as evidence of these, to the works of jurists and commentators who by years of labor, research, and experience have made themselves peculiarly well acquainted with the subjects of which they treat.