Wallen v. Williams was a case heard by the United States Supreme Court in 1813. The dispute arose when William Wallen, an African American man from Virginia, sued for his freedom from John Williams of Maryland. Wallen had been held as a slave since 1790 and argued that he should be freed because he had lived in Pennsylvania for more than six months prior to being brought back into slavery in Maryland. The court found that under the laws of both states at the time, slaves were considered personal property and could not be taken out of state without their owner's permission or risk losing their status as slaves; therefore, they ruled against Wallen on this basis. However, they also noted that if any other legal argument existed which would support his claim to freedom then it should be presented before a lower court where it could receive full consideration.

In Wallen v. Williams, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving citizens of different states. The majority opinion held that it did not have such authority and dismissed the case. However, Justice Johnson dissented from this decision on two grounds: firstly, he argued that there was no constitutional provision prohibiting state courts from exercising jurisdiction in cases between citizens of different states; secondly, he contended that if Congress had intended to limit state court power in such matters they would have done so explicitly rather than leaving it open for interpretation by the judiciary. He concluded his dissent by noting that while Congress may be able to restrict or expand judicial powers as necessary through legislation, any attempt at doing so should be clear and unambiguous instead of relying on inferences drawn from other laws or precedents.