One Nation Under Law examines the creation of the Court and follows it through the brink of the Civil War, paying particular attention to the fourth chief justice of the Supreme Court -- John Marshall -- and to his successor, Roger Taney. Marshall presided over one of the most famous cases before the Court; Taney, over one of the most infamous. In Marbury v. Madison (1803), Marshall used an obscure case involving an unsigned judicial appointment as an opportunity to assert the Court's most important power -- that of judicial review, which gives federal courts the right to strike down laws that clash with the Constitution. A half century later, in Dred Scott v. Sandford (1857), Taney exercised that same power against the national government, this time to protect slavery.