Payne v. Hook was a United States Supreme Court case that was decided in 1868. The case involved a dispute between two parties over the ownership of a slave named Mary. The plaintiff, Payne, claimed that he had purchased Mary from Hook, while Hook argued that he had only loaned Mary to Payne. The Supreme Court ultimately ruled in favor of Payne, finding that he had indeed purchased Mary from Hook. The Court's decision was based on the fact that Payne had paid Hook a sum of money for Mary, and that Hook had accepted the payment. The Court also noted that Hook had not taken any steps to reclaim Mary after the payment had been made. The Court concluded that this was sufficient evidence to establish that Payne had purchased Mary from Hook. The Court's decision in Payne v. Hook was significant because it established that a contract for the sale of a slave was legally binding. This ruling was important in the context of the Civil War, as it provided legal protection for those who had purchased slaves prior to the war. The decision also helped to clarify the legal status of slaves in the United States, as it established that they could be bought and sold like any other property.

In Payne v. Hook, the Supreme Court was tasked with determining whether a state court had jurisdiction over a case involving two citizens of different states. The majority opinion held that the state court did have jurisdiction and could proceed to hear the case. However, Justice Field dissented from this decision on several grounds. He argued that under Article III of the Constitution, only federal courts can exercise judicial power in cases between citizens of different states; therefore, he concluded that it was unconstitutional for a state court to take up such matters as they lack authority granted by Congress or an act of Congress authorizing them to do so. Additionally, Field contended that allowing individual states to decide controversies between parties from other jurisdictions would lead to conflicting decisions and create confusion among litigants who may not be able to determine which ruling is valid in their particular situation due to varying interpretations across multiple jurisdictions. Ultimately then, Justice Field believed it was necessary for uniformity's sake for all disputes between citizens of different states should be heard exclusively by federal courts rather than those at the state level