Estes v. Gunter was a United States Supreme Court case that addressed the issue of whether a state court had the authority to issue a writ of habeas corpus to a prisoner who was being held in a federal prison. The case arose when a Texas state court issued a writ of habeas corpus to William Estes, who was being held in a federal prison in Arkansas. Estes had been convicted of a federal crime and was serving a sentence in the federal prison. The state court argued that it had the authority to issue the writ because Estes was a citizen of Texas and the writ was issued in the state of Texas. 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 authority to issue the writ in a federal prison. The Court also noted that the writ of habeas corpus was a remedy that was available only to those who were being held in state prisons. The Court concluded that the state court did not have the authority to issue the writ of habeas corpus to Estes.

In Estes v. Gunter, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a citizen of one state against another in which the amount in controversy exceeded $500. The majority opinion held that it did not have such jurisdiction and reversed the judgment of the lower court. Justice Field dissented from this decision, arguing that under Article III of the Constitution, Congress has given federal courts exclusive original jurisdiction over cases where citizens of different states are involved and thus any case involving more than $500 should be heard by them rather than by state courts. He argued further that if Congress intended for these types of cases to be heard only in federal courts then they would have provided for it explicitly when granting those powers to them through Article III. Therefore he concluded that since no such explicit provision exists, then there is nothing preventing states from exercising their own judicial power with regard to controversies between its citizens and those from other states as long as they do not exceed $500 in value or involve matters arising out of foreign countries or international law issues.