Ex parte Milligan
The Court ruled that a military commission had no legal authority to try, convict, and sentence Lambdin Milligan, a civilian in Indiana, to death, because the ordinary federal courts there were open and functioning the whole time.
The decision limits how far the government can use military tribunals against civilians during wartime, holding that martial law cannot replace the civil courts and jury trials guaranteed by the Constitution wherever those courts are actually able to operate.
How it got here: Milligan petitioned the federal Circuit Court for habeas relief; the judges split on whether to grant it, so they certified three questions to the Supreme Court.
The Case in Depth
What happened
Lambdin Milligan, a longtime Indiana resident who was never in the military, was arrested at home in October 1864 by army order, accused of conspiring against the Union during the Civil War. A military commission in Indianapolis tried him, found him guilty, and sentenced him to hang. A federal grand jury later met in Indiana but never indicted him for anything.
The question before the Court
Could the Army use a military tribunal to try and sentence a civilian to death during the Civil War, even though he lived in a state where the regular courts were open and running?
Why it matters
The ruling means that during future wars or emergencies, civilians living in places where civilian courts remain open cannot be pulled into military tribunals and denied jury trials, even if the government claims wartime necessity. It set a durable check on presidential and military power over ordinary citizens not affiliated with the armed forces.
What changes now
The ruling ordered Milligan discharged from military custody. Because this was a final decision on the certified questions, there was no remand for further proceedings; the case became the Supreme Court's lasting statement on the limits of military tribunals over civilians and on when martial law can override normal constitutional protections.
What this does not decide
The majority held Congress had no power at all to authorize military trials of civilians where the courts were open. Four justices, in a separate opinion, agreed Milligan must be freed but disagreed with that broader claim, saying Congress could have authorized such tribunals in genuinely dangerous districts like wartime Indiana — it simply had not done so.
Concurrences and dissents
Concurrence — Justice Chase
Chief Justice Chase and three colleagues agreed Milligan must be discharged under the 1863 Habeas Corpus Act, but disagreed with the majority's broader claim that Congress could never authorize military trials of civilians in threatened areas. They argued Congress's war powers could support such commissions in places like wartime Indiana, even though Congress had not actually used that power here.
How the Court got there
The legal reasoning, step by step
- The Court first confirmed it had authority to answer the certified questions, reasoning that a habeas petition becomes a genuine legal 'cause' once filed, even before a formal return, so a split among the circuit judges could properly be sent up for decision.
- The Court then applied the 1863 Habeas Corpus Act, which required that anyone detained by presidential authority (and not a prisoner of war) be released if a grand jury met and adjourned without indicting him; because that happened here, the Act itself entitled Milligan to be freed from military custody.
- Turning to the constitutional question, the Court held that military trials of civilians are permissible only where actual war has closed the civil courts and made ordinary justice impossible — a state of affairs called martial law.
- Because Indiana's federal and state courts remained open, functioning, and unobstructed throughout the period in question, the Court found no factual basis for treating the state as a war zone where martial law could apply.
- The Court concluded that neither the President nor Congress could authorize a military commission to try a civilian for ordinary crimes in a place where the civil courts were open, because doing so would strip him of the grand jury and jury trial rights guaranteed by the Fifth and Sixth Amendments.
- Having found no lawful basis for the military trial, the Court held the commission lacked jurisdiction over Milligan and that he was entitled to be discharged from custody under the 1863 Act.
Doctrinal impact
Cases affected by this decision
Distinguishes Luther v. Borden
The Court said that case only upheld a state's use of militia to suppress an armed rebellion, not federal military trials of civilians.