Muller et al. v. Ehlers 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 the state court issued a writ of habeas corpus to a prisoner who was being held in a federal prison in Wisconsin. The prisoner, Ehlers, had been convicted of a crime in Wisconsin and was serving his sentence in a federal prison. The state court argued that it had the authority to issue the writ of habeas corpus because the prisoner was being held in a state 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 authority to issue it. The Court also noted that the writ of habeas corpus was a remedy that was available only to prisoners who were being held in federal prisons. Therefore, the state court did not have the authority to issue the writ of habeas corpus to Ehlers.

Justice Field delivered the dissenting opinion in Muller et al. v. Ehlers, arguing that the majority's decision was contrary to established precedent and would lead to unjust results for plaintiffs seeking relief from a court of equity. He argued that under existing law, courts of equity had jurisdiction over cases involving fraud or mistake when there were no adequate legal remedies available, and he noted that this case involved both elements: an alleged fraudulent conveyance by defendants as well as a lack of any other remedy for plaintiff’s damages due to their inability to prove title in themselves. Justice Field further argued that even if it could be shown that the deed was not fraudulent on its face, it still did not necessarily follow that plaintiff should be denied equitable relief since they may have been able to show fraud through extrinsic evidence such as testimony or documents outside of what is contained within the deed itself. In conclusion, Justice Field asserted his belief that denying equitable relief in this instance would result in injustice being done against those who are unable to obtain justice at law due solely because they cannot prove title in themselves; thus he concluded with urging reversal of judgment rendered by the lower court so as allow plaintiffs access into a court where they can seek appropriate redress for their grievances