Ex Parte Milligan
The Supreme Court ruled that the military commission which tried and sentenced Lambdin Milligan, an Indiana civilian accused of plotting against the Union war effort, had no legal authority to do so because the ordinary civilian courts in Indiana were open and operating.
The decision drew a firm line against using military tribunals to try civilians outside the war zone, holding that neither the President nor Congress could suspend jury trials and constitutional protections for citizens in places where the civil courts still functioned, even during wartime.
How it got here: Milligan sought habeas corpus in the federal Circuit Court for Indiana; the two judges there disagreed and certified the key questions, including the commission's jurisdiction, to the Supreme Court.
The Case in Depth
What happened
During the Civil War, Lambdin Milligan, a civilian who had lived in Indiana for twenty years and never served in the military, was arrested at his home, tried by a military commission in Indianapolis on charges including conspiracy and disloyal practices, and sentenced to hang. Indiana's civilian courts remained open throughout this period and never stopped operating.
The question before the Court
Could the Army put an Indiana civilian on trial before a military tribunal and sentence him to death, even though the regular courts in his state were open and functioning?
Why it matters
The ruling protected civilians from being hauled before military tribunals whenever a president or military commander felt it convenient during a national crisis. It set a lasting marker that wartime emergency powers do not erase jury trials and other constitutional protections for ordinary citizens in places where civilian courts keep working.
What changes now
The Court's answers to the certified questions directed the Circuit Court to issue the writ and discharge Milligan under the 1863 habeas corpus statute, since the military commission's judgment was void for lack of jurisdiction. This was a final merits decision; no further trial by military authority was possible, though Milligan could theoretically have faced later prosecution in an ordinary civilian court, which never occurred. Four justices, in a separate opinion by the Chief Justice, agreed with discharging Milligan but would have held that Congress could have authorized such military trials even where civil courts were open.
What this does not decide
The Chief Justice's separate opinion, joined by three other justices, stressed that the Court was not deciding whether Congress itself could ever authorize military trials of civilians in places where civil courts remained open; those four justices believed Congress had that power even though it had not used it here. The majority opinion's broader language questioning whether any branch could authorize such trials was therefore not something all nine justices agreed to.
Concurrences and dissents
Concurrence — Justice Chase
Chief Justice Chase, joined by Wayne, Swayne, and Miller, agreed Milligan must be discharged under the 1863 habeas corpus statute but rejected the majority's broader claim that no branch of government could ever authorize military trials of civilians where civil courts were open. He argued Congress had constitutional power, under its authority to raise armies and declare war, to authorize such commissions in genuinely dangerous districts, even though Congress had chosen not to exercise that power in Indiana.
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 corpus petition becomes a 'suit' or 'cause' as soon as it is filed, so a division of opinion between the two circuit judges over Milligan's petition could properly be sent up for decision even without a return to the writ yet filed.
- The Court then asked where judicial power to try and punish crimes comes from under the Constitution, and found that it is vested exclusively in courts 'ordained and established' by Congress under Article III — a military commission created solely by a military commander's order is not such a court and cannot exercise judicial power over civilians.
- The Court examined the Fifth and Sixth Amendment jury-trial guarantees, which exempt only people actually serving in the land or naval forces or militia in active service; because Milligan was a civilian never in that service, these guarantees fully applied to him regardless of the ongoing war.
- The Court articulated the controlling rule for when military rule can override civilian courts: martial law can only govern where actual, present war has closed the civil courts and made ordinary justice physically impossible, not merely because a state lies within a broadly defined military district or fears future invasion.
- Applying that rule, the Court found Indiana's civil courts open, staffed, and actively trying similar cases throughout the relevant period, so no military necessity ever existed there to justify replacing a jury trial with a military commission.
- Because the underlying trial and sentence had no jurisdictional foundation, the Court concluded that Milligan's imprisonment could not stand and that the habeas corpus act of 1863 entitled him, on the admitted facts, to be freed from military custody once a grand jury had met and declined to indict him.
Doctrinal impact
Cases affected by this decision
Distinguishes Luther v. Borden (7 Howard 1)
The Court said this earlier case about a state's own militia power was misread and does not support using martial law against civilians here.
Reaffirms Ex parte Vallandigham (1 Wallace 243)
Confirms that military commissions are not courts and their proceedings cannot be reviewed by ordinary appeal.
Reaffirms Bollman's case
Relies on this earlier ruling that courts, not just individual judges, can issue habeas corpus to examine imprisonment.