Why must a law be struck down if it violates the Constitution?
Decision of the Supreme Court in Marbury v. Madisondelivered by Chief Justice John Marshall"So, if a law be in opposition to the Constitution, if both the law and the Constitution apply to a particular case, … the Court must determine which of these conflicting rules governs the case. This is of the very essence of judicial duty.…The particular phraseology [wording] of the Constitution of the United States confirms and strengthens the principle, supposed to be essential to all written Constitutions, that a law repugnant to the Constitution is void, and that courts, as well as other departments, are bound by that instrument."