The Hart case was a dispute between two parties over the ownership of a slave named Eliza. The plaintiff, William H. Hart, claimed that he had purchased Eliza from her previous owner in 1859 and thus owned her outright. However, the defendant argued that they were entitled to possession of Eliza because she had been promised to them by her former master before his death in 1860. The Supreme Court ultimately sided with the plaintiff and held that since Hart had acquired title to Eliza prior to any promise made by her former master, he was legally entitled to possess her as his property. This decision established an important precedent for future cases involving disputes over ownership rights concerning slaves or other forms of personal property; namely, it confirmed that whoever has legal title at the time is considered rightful owner regardless of any promises made beforehand by another party who may have previously possessed such property.

In The Hart, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a citizen of another state. Justice Field delivered the dissenting opinion in which he argued that states do not have jurisdiction over citizens of other states unless they are present within their boundaries and subject to their laws. He further stated that it is only when such persons voluntarily submit themselves to the authority of a foreign government or enter into contracts with its citizens, that they can be held liable for any obligations incurred while there. Furthermore, Justice Field asserted that if Congress has not given permission for suits against non-residents in state courts then those courts cannot exercise such power without infringing upon federal law. Finally, he concluded by stating his belief that allowing states to exercise this kind of authority would lead to confusion and conflict between different jurisdictions as well as unnecessary litigation costs for all parties involved.