Ex Parte Milligan

A habeas petition was a legal "cause" or "suit" from the moment Milligan invoked the court's authority to obtain his liberty. The Court rejected the argument that there could be no certifiable division until a writ issued and the custodians formally made a return. A court may examine the petition itself and refuse the writ if the stated facts show that the prisoner would necessarily be remanded; thus, the legal questions arose in a pending cause.

The purpose of the 1802 certificate-of-division statute was to prevent a failure of justice when the two judges of a circuit court disagreed on a controlling legal question. Reading the statute to deny review merely because Milligan had initiated the proceeding alone would leave a prisoner without a remedy precisely when the judges were divided over whether he could be lawfully detained or executed.

The Court also found that the district attorney's appearance and agreement to submit the application confirmed that the government had notice and an opportunity to contest the petition. The Court treated its answers as final on the certified questions, while recognizing that no person would be precluded from raising issues that might arise on a later return to the writ.

The 1863 Act authorized the President to suspend the privilege of the writ of habeas corpus during the rebellion, but it also imposed protections for persons detained under presidential authority in states where federal courts continued to function. It required release, on prescribed terms, when a grand jury convened and adjourned without indicting or presenting the detained person.

Milligan alleged every fact needed to invoke the statute: he was an Indiana citizen, not a member of the armed services, was held under presidential authority, and a federal grand jury had met and adjourned without bringing charges against him. The Court rejected the technical objection that he failed to allege whether the executive had furnished judges a statutory prisoner list, because Milligan could not be expected to know that fact and the absence of the list could not defeat the statutory protection.

Suspending the privilege of habeas corpus did not itself erase the writ or authorize indefinite confinement. The writ could still issue, and the court would determine on the return whether the suspension barred further relief. Here, because Milligan's military conviction was unlawful and the statutory conditions for relief had occurred, the Act entitled him to release from military detention.

The Constitution assigns criminal adjudication to courts established by Congress and protects criminal defendants through grand-jury indictment, trial by jury, due process, and related safeguards. Milligan was a civilian who had never joined the military, and the charges against him were criminal offenses that the ordinary federal courts could hear. A military commission created by executive authority was not a court ordained and established by Congress and could not exercise the judicial power necessary to try and punish him.

The Constitution's military exception applies to cases arising in the land or naval forces and to the militia in actual service. Congress may establish military tribunals and procedures for persons properly subject to military discipline, but Milligan did not fall within that category. The Court held that the constitutional guarantees of criminal procedure protect civilians even during war and cannot be displaced by an executive claim of military necessity.

The Court distinguished the suspension of habeas corpus from the power to impose military trials. Suspension may permit the government to hold a dangerous person without immediately producing him in response to the writ, but it does not authorize punishment without the ordinary criminal process. The Constitution expressly permits suspension of that one privilege in rebellion or invasion; it does not say that a suspended privilege eliminates the rights to indictment, jury trial, and due process.

Martial rule may be justified only where actual war has displaced the civil courts and made the ordinary administration of justice impossible. Necessity both creates and limits that exceptional authority. Indiana was not such a place: federal authority was undisputed, courts were open, juries were available, and judicial process was unobstructed. A threatened invasion or a military department designation could not transform Indiana into a locality governed by martial law.

The Court stressed that constitutional protections apply in war as well as peace. Accepting the government's theory would allow military commanders, with executive approval, to replace civil law with their own will throughout broad military districts. The Court regarded that result as incompatible with republican government and the Constitution's command that the military remain subordinate to civil law.