What 1789 law established the original structure of the United States federal court system?

The 1789 law that established the original structure of the United States federal court system was the Judiciary Act of 1789.

Congress passed the act during the First United States Congress, and President George Washington signed it on September 24, 1789. The Constitution had created a Supreme Court but left Congress to establish the lower federal courts, their organization, and much of their jurisdiction. The Judiciary Act supplied that missing structure.

The law created a Supreme Court with a chief justice and five associate justices. It also established federal district courts and circuit courts, along with the offices of United States attorney and United States marshal. The act divided the country into judicial districts and defined how cases could move through the federal system.

The Judiciary Act was not the Constitution and did not create the Supreme Court itself; Article III created that constitutional institution. The act was later amended several times as the nation expanded and Congress changed the federal judiciary. Its original framework shaped federal court administration during the early republic.