Marbury v. Madison strengthened the federal judiciary by establishing for it the power of judicial review, by which the federal courts could declare legislation, as well as executive and administrative actions, inconsistent with the U.S. Constitution (“unconstitutional”) and therefore null and void. The exercise of judicial review helped the federal judiciary check the actions of Congress and the president and thereby remain a coequal branch of government alongside the legislative and executive branches.

Marbury v. Madison arose after the administration of U.S. Pres. Thomas Jefferson withheld from William Marbury a judgeship commission that had been formalized in the last days of the preceding John Adams administration but not delivered before Jefferson’s inauguration. Ruling on a request by Marbury, the U.S. Supreme Court held that it could not order the surrender of the commission because the law that would have empowered it to do so was unconstitutional.

Marbury v. Madison is important because it established the power of judicial review for the U.S. Supreme Court and lower federal courts with respect to the Constitution and eventually for parallel state courts with respect to state constitutions. The exercise of judicial review would help to ensure that the judiciary remained a coequal branch of government alongside the legislative and executive branches.