Can civilians be tried in military court? Almost never. The Constitution and roughly 160 years of Supreme Court precedent reserve courts-martial for people in uniform and keep military jurisdiction off civilians. A few narrow exceptions exist: civilian contractors and employees accompanying the armed forces overseas during a war or contingency operation, military retirees drawing retirement pay, non-citizen enemy belligerents facing military commissions, and the extreme scenario of martial law. Outside those situations, a civilian accused of a crime belongs in civilian court.
The Default Rule: Civilians Belong in Civilian Court
The controlling case is Ex parte Milligan, decided in 1866. The federal government had arrested Lambdin Milligan, a civilian in Indiana, and tried him before a military commission for conspiring against the Union during the Civil War. He had no military connection, and Indiana’s civilian courts were open the entire time. The Supreme Court unanimously ruled that the commission had no authority to try him.1Justia U.S. Supreme Court Center. Ex parte Milligan, 71 US 2 (1866)
The Court’s language was categorical. Constitutional protections like trial by jury apply “equally in war and in peace” and “cover with the shield of its protection all classes of men, at all times and under all circumstances.” Where civilian courts are open and functioning, military tribunals have no business trying civilians. That principle still anchors the law today.
Civilians Working With the Military Overseas
The biggest real-world exception involves civilians who deploy alongside troops. The Uniform Code of Military Justice extends jurisdiction to people “serving with or accompanying an armed force in the field” during a declared war or a contingency operation.2Office of the Law Revision Counsel. 10 US Code 802 – Art. 2. Persons Subject to This Chapter That means civilian logistics workers, defense contractors, and government employees embedded with U.S. forces in a combat zone.
Before 2006, this authority reached only civilians in a formally declared war, and the United States has not declared war since World War II. The John Warner National Defense Authorization Act for Fiscal Year 2007 added “or a contingency operation” to the statute, dramatically broadening its reach. The change responded to incidents involving contractors in Iraq and Afghanistan who had committed serious crimes and fallen through jurisdictional cracks.
A separate clause covers civilians “employed by, or accompanying the armed forces outside the United States” more generally, though it is subject to any applicable treaty or international law. The constitutional reach of that broader clause has been heavily litigated and remains contested.
The Usual Alternative: Federal Court Under MEJA
Military jurisdiction is not the only route. The Military Extraterritorial Jurisdiction Act lets federal civilian courts prosecute anyone employed by or accompanying the armed forces abroad for conduct that would be a felony under U.S. law.3Office of the Law Revision Counsel. 18 US Code 3261 – Criminal Offenses Committed by Certain Members of the Armed Forces and by Persons Employed by or Accompanying the Armed Forces Outside the United States The Department of Defense and Department of Justice coordinate on which route to use, weighing the seriousness of the offense, evidence and witness availability, impact on military operations, and logistics. Federal prosecution under MEJA is often preferred because it sidesteps the constitutional questions around court-martialing civilians. Military jurisdiction tends to fill the gap only where a stateside trial is impractical.
Military Spouses, Dependents, and Civilian Employees
If you are a military spouse, a dependent living on an overseas base, or a civilian employee of the Department of Defense stationed abroad, the military cannot court-martial you in peacetime. The Supreme Court settled this in a series of cases.
In Reid v. Covert (1957), two wives of service members killed their husbands on overseas bases and were tried by court-martial. The Supreme Court reversed both convictions, holding that civilian dependents abroad could not be tried by military courts for capital offenses in peacetime. Justice Black wrote that constitutional protections follow American citizens everywhere and “cannot be set aside by an act of Congress.”4Justia U.S. Supreme Court Center. Reid v. Covert, 354 US 1 (1957)
Three years later, Kinsella v. Singleton extended the rule to non-capital offenses against dependents,5Library of Congress. Kinsella v. Singleton, 361 US 234 (1960) and Grisham v. Hagan closed the door on civilian employees, holding they too are protected by Article III and the Fifth and Sixth Amendments and cannot be court-martialed overseas in peacetime.6Justia U.S. Supreme Court Center. Grisham v. Hagan, 361 US 278 (1960)
Former Service Members and Retirees
Being discharged and being retired are two different things under military law, and the difference matters.
A discharged former service member is a civilian. In United States ex rel. Toth v. Quarles (1955), Robert Toth had been honorably discharged from the Air Force and taken a civilian job. Five months later, military authorities arrested him on murder charges for an act allegedly committed while he was still serving in Korea. The Supreme Court held flatly that “Congress cannot subject civilians like Toth to trial by court-martial” and that former service members are entitled to the safeguards of the regular courts.7Library of Congress. United States ex rel. Toth v. Quarles, 350 US 11 (1955) Once you are out, you are out.
Retirees are treated differently. The UCMJ specifically lists “retired members of a regular component of the armed forces who are entitled to pay” as persons subject to military jurisdiction.2Office of the Law Revision Counsel. 10 US Code 802 – Art. 2. Persons Subject to This Chapter The theory is that a retiree drawing retirement pay maintains a continuing obligation to the armed forces, including a duty to return to active duty if recalled.
Whether that passes constitutional muster has been litigated. In Larrabee v. Del Toro, a federal district court ruled in 2020 that court-martial jurisdiction over Fleet Marine Reservists was unconstitutional. The D.C. Circuit reversed in 2022, reasoning that retirees maintain a “formal relationship with the military that includes a duty to obey military orders,” which was enough to sustain jurisdiction. The Supreme Court has not taken up the question directly. For now, if you are a military retiree drawing retirement pay, you should assume you can be court-martialed for offenses committed after retirement.
Non-Citizen Enemy Belligerents and Military Commissions
A separate system exists outside the UCMJ. Under the Military Commissions Act, the United States can try any non-citizen classified as an “unprivileged enemy belligerent” before a military commission. That category covers anyone who has fought against the United States or its coalition partners, materially supported such fighting, or was part of al Qaeda at the time of the alleged offense.8Office of the Law Revision Counsel. 10 USC 948a – Definitions
The offenses triable this way include murder of protected persons, attacking civilians, taking hostages, using poison or biological weapons, terrorism, and providing material support for terrorism. Several carry the death penalty.9Office of the Law Revision Counsel. 10 USC 950t – Offenses Triable by Military Commission This is the framework behind the Guantanamo Bay commissions.
U.S. citizens cannot be tried by military commission under this statute. The law reaches only “aliens.” An American citizen accused of the same conduct faces federal civilian court.
Martial Law
The most extreme scenario for a civilian is martial law. If civilian government collapses in a catastrophic emergency and civilian courts stop functioning, military authority can temporarily fill the void, and military tribunals can take over the work of civilian courts. That follows the logic of Milligan: the protection against military trials for civilians rests on civilian courts being open. If they are not, the calculus shifts.
As a practical matter, martial law has been declared in the United States only at the state level, by governors exercising emergency powers. The Constitution does not explicitly give the President power to declare martial law, and the prevailing view is that actions taken under any such declaration remain subject to federal court review once courts function again.10Constitution Annotated. ArtII.S2.C1.1.14 Martial Law Generally Full martial law displacing civilian courts has been vanishingly rare in American history.
What a Military Trial Looks Like if You Face One
A court-martial is not a federal trial with different insignia. The most consequential difference is the absence of a jury. Courts-martial are not subject to the Sixth Amendment’s jury trial requirement.11United States Court of Appeals for the Armed Forces. First Principles – Constitutional Matters – Right to a Jury Trial Instead of twelve randomly selected civilians, your case is heard by a panel of military officers selected by the convening authority, meaning the commanding officer who referred the charges. The convening authority picks panel members based on their “age, education, training, experience, length of service, and judicial temperament.”12Office of the Law Revision Counsel. 10 US Code 825 – Art. 25. Who May Serve on Courts-Martial That is a sharp departure from the random cross-section civilian juries are meant to represent.
Sentencing works differently too. In federal civilian court, a judge imposes the sentence under federal sentencing guidelines. In a court-martial, the panel decides the sentence, with different vote thresholds depending on the punishment.
Some safeguards do apply. A person facing a general court-martial has the right to be told the specific charges, to be represented by a military defense attorney at no cost, and to hire a civilian attorney as well. The accused can present evidence, cross-examine witnesses, and cannot be compelled to testify. After conviction, appeals run through the service Court of Criminal Appeals and, when warranted, the Court of Appeals for the Armed Forces. The structural differences remain significant enough that the Supreme Court has consistently treated court-martial jurisdiction over civilians as something requiring strong justification rather than a default.