Ex Parte Tobias Watkins was a case heard by the United States Supreme Court in 1833. The case involved an appeal from the Circuit Court of Georgia, where Tobias Watkins had been convicted of larceny and sentenced to five years' imprisonment. In his appeal, he argued that his conviction should be overturned because it violated both state and federal constitutional protections against double jeopardy. Specifically, he claimed that since he had already been tried for the same crime in another court before being brought to trial again in Georgia, this constituted double jeopardy under both state and federal law. The Supreme Court ultimately agreed with him; they ruled that due process requires a person cannot be put on trial twice for the same offense unless there is new evidence or some other compelling reason why a second trial is necessary. As such, they reversed his conviction and set aside his sentence as unconstitutional under both state and federal law.

In Ex Parte Tobias Watkins, the Supreme Court was asked to decide whether a writ of habeas corpus should be issued in order for an individual to be released from prison. The majority opinion held that the writ should not issue because it would interfere with state proceedings and violate principles of comity between states. Justice McLean dissented, arguing that Congress had given federal courts exclusive jurisdiction over cases involving prisoners who were unlawfully detained by state authorities. He argued that this power could not be taken away without explicit action by Congress and thus the court had no choice but to grant the writ of habeas corpus requested in this case. Furthermore, he noted that if such requests were denied then individuals would have no recourse against arbitrary imprisonment or other violations of their rights under law.