What major constitutional principle did Marbury v. Madison (1803) establish for the U.S. government?

• A. The President can veto Supreme Court decisions.
• B. Judicial review—the power of the courts to declare laws unconstitutional.
• C. The Supreme Court has no authority to review federal statutes.
• D. Congress can override court rulings by simple majority.

Answer: (B)

Judicial review—the power of the courts to declare laws unconstitutional.

Marbury v Madison established that the Constitution is the supreme law of the land and that the judiciary has the authority to interpret it and strike down any law or government action that conflicts with it. The decision arose from a dispute about a writ of mandamus, but the key move was recognizing that a portion of the Judiciary Act of 1789 extended the Court’s powers beyond what the Constitution allowed. Because of that, the Court concluded that portion was unconstitutional, and in doing so it placed the authority to interpret the Constitution in the hands of the courts.

This creates a crucial check and balance: if Congress or the President enacts something that violates the Constitution, the courts can invalidate it. The other options describe powers that aren’t how this decision functions—no veto power for the President over Court rulings, the Court does have authority to review statutes, and Congress cannot override Supreme Court decisions by a simple majority.