Knode v. Williamson was a United States Supreme Court case that dealt with the issue of whether a state court had the authority to issue a writ of error to a federal court. The case arose when the plaintiff, Knode, sued the defendant, Williamson, in a state court in Pennsylvania. The state court issued a writ of error to the federal court, which the defendant argued was an unconstitutional exercise of power. The Supreme Court held that the state court did not have the authority to issue a writ of error to a federal court. The Court reasoned that the state court was not a court of competent jurisdiction to review the decision of the federal court, and that the writ of error was therefore invalid. The Court also held that the writ of error was not necessary to protect the rights of the parties, as the federal court had already issued a judgment in the case. The Court concluded that the writ of error was an unconstitutional exercise of power by the state court.

In Knode v. Williamson, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a non-resident against another non-resident in which the cause of action arose out of a contract made within that state. The majority opinion held that such jurisdiction did exist and affirmed the judgment of the lower court. However, Justice Field dissented from this decision on two grounds: firstly, he argued that there was no precedent for allowing states to exercise jurisdiction over actions between non-residents; secondly, he asserted that if such power were allowed it would be unconstitutional as it would violate Article IV Section 1 of the Constitution which guarantees citizens "the Privileges and Immunities" clause protecting them from being sued in any other State than their own without their consent. He concluded his dissent by stating “I am unable to assent to so great an extension” beyond what is provided for under existing law or constitutional provisions.