Ehrhardt v. Hogaboom 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 who was being held in a federal prison. The case arose when a prisoner, Ehrhardt, was held in a federal prison in California and sought a writ of habeas corpus from the state court. The state court granted the writ, but the federal government argued that the state court did not have the authority to issue the writ. 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 issue the writ. The Court also noted that the writ of habeas corpus was a federal remedy and that the state court did not have the power to issue the writ. The Court's decision in Ehrhardt v. Hogaboom established that state courts do not have the authority to issue writs of habeas corpus to prisoners held in federal prisons. The decision also established that the writ of habeas corpus is a federal remedy and that state courts do not have the power to issue the writ.

Justice Field delivered the dissenting opinion in Ehrhardt v. Hogaboom, arguing that the majority's decision was contrary to precedent and public policy. He argued that a contract between two parties should be enforced according to its terms unless it is against public policy or illegal. In this case, he believed there was no reason why the contract should not have been enforced as written because it did not violate any laws or policies of California where it had been made. Furthermore, Justice Field noted that if contracts were allowed to be modified after they had already been agreed upon by both parties then people would never feel secure entering into agreements with one another since their promises could always be broken later on without consequence. He concluded his dissent by stating that while courts may modify contracts when necessary for justice and equity, such modifications must only occur within certain limits which were exceeded in this particular case due to lack of evidence supporting an alteration of the original agreement between Ehrhardt and Hogaboom