Kail et al. v. Wetmore 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 habeas corpus to a prisoner held in federal custody. The case arose when the state of Pennsylvania issued a writ of habeas corpus to a prisoner held in federal custody in the state of New York. The prisoner, Wetmore, argued that the state court did not have the authority to issue the writ, as the federal government had exclusive jurisdiction over the matter. The Supreme Court ultimately ruled in favor of Wetmore, holding that the state court did not have the authority to issue the writ. The Court reasoned that the federal government had exclusive jurisdiction over matters involving federal prisoners, and that the state court did not have the authority to interfere with the federal government's authority. The Court also noted that the writ of habeas corpus was a federal prerogative, and that the state court did not have the authority to issue such a writ. In conclusion, the Supreme Court held that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in federal custody. The Court reasoned that the federal government had exclusive jurisdiction over matters involving federal prisoners, and that the state court did not have the authority to interfere with the federal government's authority.

In Kail et al. v. Wetmore, the Supreme Court was tasked with deciding whether a state court had jurisdiction to hear a case involving non-residents of that state and their property located in another state. The majority opinion held that the lower court did not have jurisdiction over this matter because it involved citizens from two different states and real estate located in one of those states; thus, it should be heard by federal courts instead. However, Justice Field dissented from this decision on the basis that there is nothing unconstitutional about allowing a state court to exercise its authority over matters between individuals who are both citizens of other states but whose dispute involves land within its own borders. He argued further that if such disputes were only allowed to be heard by federal courts then many cases would never make it into any courtroom due to lack of resources or time constraints for litigants living far away from where they need to file suit in order for their claims to be heard at all. Ultimately, Justice Field concluded his dissent by stating he believed Congress intended for these types of suits between non-residents concerning property within a particular state's boundaries could still be adjudicated through local tribunals as long as no constitutional rights were violated in doing so