Marbury v Madison was one of the most important, if not the most important legal case in the United States. The case affirmed that the US Constitution is the paramount law by which the Supreme Court and Congress are held, and that Congress cannot pass laws that are in opposition to the Constitution. Marbury v Madison was brought to the court after the presidential election of 1800, where Thomas Jefferson won the presidency from John Adams. Before the office was vacated by Adams, his party attempted to fill many Federal offices with staff loyal to the Federalist party. This involved Adam's nominating them, the Senate approving the nomination, and the commissions being sent to the nominees. The intent was to have these nominations delivered before Thomas Jefferson took office, but some were delivered after Jefferson was sworn in. Jefferson tasked his Secretary of State, James Madison to withhold the commissions that had not yet been delivered.
Madison complied and withheld the commissions, causing William Marbury, who was due to receive his commission, to file a suit in the US Supreme Court against Madison. His aim was to have the Court issue a 'writ of mandamus', a form of order mandating that an elected official perform an action they are legally obliged to perform. The Supreme Court found that while withholding the commissions was illegal, the Supreme Court did not in fact have the jurisdiction to issue the writ. The key part of this ruling was that Congress had passed a law that enabled the Court to action this request from Marbury, however the Court argued that the law went against the original powers in the Constitution, and thus, they "struck out' the law from Congress. This introduced the process of 'judicial review' in the United States, where the Supreme Court may 'strike out' laws passed by Congress when the law goes against or extends power further than the Constitution provides.