The Judiciary Act of 1789 established a United States Supreme Court of six judges, provided 13 district courts and 3 circuit courts. In addition, It established the Supreme Court as the mediator of all disputes between states and the federal government concerning conflicting state and federal laws.

Not long before Thomas Jefferson, who was an anti-federalists, took office, Congress, in cooperation with President John Adams, a federalist, passed the Judiciary act of 1801. This act's purpose was to limit the number of judges that Jefferson could appoint after taking office. Adams wanted the judges that he appointed to hold their positions for life. At the end of Adam's term, he quickly appointed new judges, known as the midnight judges, to fill the new judicial posts created under the act.

A clause granting the Supreme Court the right to issue writs of mandamus was declared unconstitutional by Marbury v. Madison 5 US 137 1803, the seminal case in American law. Thus the Judiciary Act of 1789 was the first act by Congress to be invalidated by the Supreme Court.