Dow v. Johnson was a United States Supreme Court case that addressed the issue of whether a state court could issue a writ of habeas corpus to a prisoner who had been convicted in a federal court. The case arose when a prisoner, Johnson, was convicted in a federal court and sentenced to imprisonment. Johnson then sought a writ of habeas corpus from a state court, claiming that his conviction was unconstitutional. The state court granted the writ, and Johnson was released from prison. The Supreme Court held that the state court did not have the authority to issue the writ of habeas corpus. The Court reasoned that the writ of habeas corpus was a federal remedy, and that the state court did not have the power to interfere with a federal court's judgment. The Court also noted that the writ of habeas corpus was a remedy of last resort, and that Johnson had not exhausted all other remedies available to him. The Court's decision in Dow v. Johnson established that state courts do not have the authority to issue writs of habeas corpus to prisoners convicted in federal courts. The decision also reaffirmed the principle that the writ of habeas corpus is a remedy of last resort, and that other remedies must be exhausted before a writ of habeas corpus can be sought.

In Dow v. Johnson, the Supreme Court was tasked with determining whether a state court had jurisdiction to hear an appeal from a probate court in another state. The majority opinion held that it did not have such authority, but Justice Field dissented on the grounds that states should be allowed to exercise their own laws and procedures when dealing with matters of probate within their borders. He argued that allowing one state's courts to interfere in another's affairs would create confusion and uncertainty for litigants who may find themselves subject to different rules depending on which court they are appealing through. Furthermore, he noted that this could lead to unequal treatment of citizens based solely on where they live or what type of case is being heard by each respective court system. Ultimately, Justice Field concluded that while there must be some limits placed upon interstate judicial proceedings due to federalism concerns, those limitations should not prevent states from exercising their own laws as long as no other party is harmed by doing so.