A more thorough explanation:

Marbury v. Madison (1803) was a case that went to the U.S. Supreme Court. It was an important case because it established the Supreme Court’s power of judicial review. This means that the Supreme Court has the authority to review legislative or executive acts and find them unconstitutional.

Here's an example: After President John Adams lost the 1800 election, but before he left office, he appointed Marbury as a justice of the peace and signed the commission. Soon thereafter, Thomas Jefferson became President of the United States and refused to allow Secretary of State James Madison to deliver the commission to Marbury. Marbury sued Madison in the Supreme Court to get his commission via a writ of mandamus.

Under Justice John Marshall, the Court specifically held that the provision in the 1789 Act granting the Supreme Court the power to issue a writ of mandamus was unconstitutional. This means that the Supreme Court cannot force the government to do something if it goes against the Constitution.

Marbury v. Madison limited federal court’s jurisdiction, but it cemented the Court’s status as the ultimate interpreter of the Constitution. This means that the Supreme Court has the final say on what the Constitution means and how it should be applied.