appeal, the U.S. government argued that it had complied with international law, under which there was precedent for the executive of a nation, through his military commanders, to exercise discretion as to whether there was an exemption of fishing vessels from prize capture. 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. Decision 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