Edward Douglass White, who served both as an Associate Justice and as Chief Justice of the United States during his long tenure on the Supreme Court (1894-1921) is notable for being the only civilly-trained Louisianan to serve on the Court. In the course of his judicial career, he relied on civilian sources in a number of his opinions. This Article explores one such example. The Selective Draft Law Cases of 1918 represents a consolidation of several lower-court challenges to the constitutionality of the conscription regime adopted by Congress at the time of America's entry into World War I. White's opinion is notable, among other reasons, for his use of Emmerich Vattel's (1714-1767) treatise Le droit des gens as a major source for his constitutional theorizing on the inherent powers of the state. After evaluating White's use of Vattel as a legal source, the final section of the Article situates White's use of Continental materials in the historical jurisprudence of that time. Law, in that school of thought, represented an admixture of human reason and historical experience. White, by looking to Continental sources, sought to expand the usual range of materials employed by historical jurisprudes and found a fit vehicle for this purpose in Vattel's theory of the state in a time of war.