Dante Figueroa, a senior legal information analyst at the Law Library of Congress: [snipped from the full posting here]:

“I have previously written about the amazing collection of Roman law resources at the Law Library of Congress.  I noted that references to Roman law have been made in arguments before, and in decisions of, U.S. courts, including the U.S. Supreme Court.  In fact, the use of and reference to Roman law by U.S. courts has been widely documented.  A U.S. law professor has stated that the use of Roman law by U.S. courts was “an integral part of the larger jurisprudential process by which American jurists reached back to find a line of argument to be employed in understanding the case.”  (Samuel J. Astorino, Roman Law in American Law: Twentieth Century Cases of the Supreme Court, 40 Duq. L. Rev. 627 (2002).) Some authors note that Roman law had an enormous influence on legal education and legal writers from “the colonial period to the time of the Dred Scott decision [1857].” (Steven Calabresi & Stephanie Dotson Zimdahl, The Supreme Court and Foreign Sources of Law: Two Hundred Years of Practice and the Juvenile Death Penalty Decision , 47 Wm. & Mary L. Rev. 743, 761 (2005).)  Another author argues that the use of Roman law by U.S. courts diminished by the 1920s for two reasons: World War I had “generated a broad anti-German feeling, thereby closing off a major source of civil law influence,” and due to the “dramatic decline in language skills, especially Greek and Latin, among lawyers and jurists.”  (Astorino, supra, at 628).  Research by academics has shown, however, that the U.S. Supreme Court did continue to make some use of Roman law during the twentieth century.  (Calabresi, supra, at 760.)…”