Hart v. Sansom & Another 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 mandamus to a county court. The case was brought by Hart, who was a resident of the state of Pennsylvania. Hart had filed a petition in the county court of Philadelphia County, seeking a writ of mandamus to compel the county court to issue a writ of habeas corpus to the sheriff of the county. The county court refused to issue the writ, and Hart appealed to the Supreme Court of Pennsylvania. The Supreme Court of Pennsylvania held that the county court had the authority to issue the writ of mandamus, and that the writ should be issued. The Supreme Court of the United States affirmed the decision of the Supreme Court of Pennsylvania. The Court held that the state court had the authority to issue the writ of mandamus, and that the writ should be issued. The Court also held that the writ of habeas corpus should be issued by the county court, and that the sheriff should be compelled to obey the writ. In conclusion, the Supreme Court of the United States held that the state court had the authority to issue a writ of mandamus to the county court, and that the writ should be issued. The Court also held that the writ of habeas corpus should be issued by the county court, and that the sheriff should be compelled to obey the writ.

Justice Field delivered the dissenting opinion in Hart v. Sansom & Another, arguing that the majority had erred in its interpretation of a deed from 1848. The deed conveyed land to two individuals, with one receiving an undivided half interest and the other receiving all rights to minerals beneath it. Justice Field argued that this language did not indicate any intent by either party for joint ownership of mineral rights; rather, he believed it was meant to convey exclusive control over those resources to one individual while leaving surface rights divided between them both. He further noted that if such an arrangement were found invalid under state law then there would be no incentive for parties entering into similar agreements in future transactions as they could not rely on their enforceability. As such, Justice Field concluded that the court should have affirmed the decision of lower courts which held that only one person owned these mineral rights and thus reversed its own ruling on this matter.