One may claim that the judiciary has historically been the weakest of the three branches. In fact, its power to exercise judicial review—its sole meaningful check on the other two branches—is not explicitly granted by the U.S Constitution. The U.S. Supreme Court exercised its power to strike down congressional acts as unconstitutional only twice prior to the Civil War: in Marbury v. Madison (1803) and Dred Scott v. Sandford (1857). The Supreme Court has since then made more extensive use of judicial review.

How many times prior to Dred Scott v. Sandford had the Supreme Court exercised its power to strike down congressional acts?