Through the Judiciary Act of 1789, Washington established a six-member Supreme Court. The court was composed of one Chief Justice and five Associate Justices. The Supreme Court was given exclusive original jurisdiction over all civil actions between states, or between a state and the United States, as well as over all suits and proceedings brought against ambassadors and other diplomatic personnel; and original, but not exclusive, jurisdiction over all other cases in which a state was a party and any cases brought by an ambassador. The Court was given appellate jurisdiction over decisions of the federal circuit courts as well as decisions by state courts holding invalid any statute or treaty of the United States; or holding valid any state law or practice that was challenged as being inconsistent with the federal constitution, treaties, or laws; or rejecting any claim made by a party under a provision of the federal constitution, treaties, or laws.
Under the Supreme Court, the Judiciary Act created 13 judicial districts within the 11 states that had then ratified the Constitution (North Carolina and Rhode Island were added as judicial districts in 1790, and other states as they were admitted to the Union). Within these judicial districts were circuit courts and district courts. The circuit courts, which were composed of a district judge and (initially) two Supreme Court justices "riding circuit," had jurisdiction over more serious crimes and civil cases and appellate jurisdiction over the district courts, while the single-judge district courts had jurisdiction primarily over admiralty cases, along with petty crimes and lawsuits involving smaller claims. The circuit courts were grouped into three geographic circuits to which justices were assigned on a rotating basis.