Ex Parte Burr was a United States Supreme Court case in which the court ruled that it had no jurisdiction to issue a writ of habeas corpus for Aaron Burr, who had been charged with treason. The court held that since the crime of treason is committed against the United States as a whole, and not just one state or district, only Congress has authority to issue such writs. Furthermore, even if Congress did have such power over this particular matter, they had already declined to do so when presented with an earlier petition from Burr's lawyers. Therefore, the court concluded that it could not grant relief on behalf of Aaron Burr in this instance. This decision established precedent regarding federalism and separation of powers between branches within government by affirming each branch’s respective authority over certain matters.

In Ex Parte Burr, the Supreme Court was asked to decide whether a writ of habeas corpus should be issued for Aaron Burr. The majority opinion held that the court lacked jurisdiction and could not issue such a writ. However, Justice Johnson dissented from this decision, arguing that Congress had granted federal courts the power to issue writs of habeas corpus in certain cases and thus they did have jurisdiction over this matter. He further argued that even if there were some doubt as to their authority in issuing such a writ, it would still be appropriate for them to do so given the circumstances surrounding Aaron Burr's case. In his view, since he was being held without any formal charge or trial by an executive officer who acted on his own discretion rather than pursuant to law or judicial proceedings, it would be unjust not to grant him relief through a writ of habeas corpus.