Source: 71 U.S. 2; https://www.law.cornell.edu/supremecourt/text/71/2

Justice DAVIS delivered the opinion of the court, joined by Justices CLIFFORD, FIELD, GRIER, and NELSON.

. . . The importance of the main question presented by this record cannot be overstated, for it involves the very framework of the government and the fundamental principles of American liberty. . . .

The controlling question in the case is this: . . . had the military commission mentioned in it jurisdiction legally to try and sentence him? . . .

No graver question was ever considered by this court, nor one which more nearly concerns the rights of the whole people, for it is the birthright of every American citizen when charged with crime to be tried and punished according to law. . . . The founders of our government were familiar with the history of that struggle [the struggle to preserve liberty and to relieve those in civil life from military trials], and secured in a written constitution every right which the people had wrested from power during a contest of ages. By that Constitution and the laws authorized by it this question must be determined. The provisions of that instrument on the administration of criminal justice are too plain and direct to leave room for misconstruction or doubt of their true meaning. Those applicable to this case are found in that clause of the original Constitution which says that “the trial of all crimes, except in case of impeachment, shall be by jury,” and in the fourth, fifth, and sixth articles of the amendments. The fourth proclaims the right to be secure in person and effects against unreasonable search and seizure, and directs that a judicial warrant shall not issue “without proof of probable cause supported by oath or affirmation.” The fifth declares “that no person shall be held to answer for a capital or otherwise infamous crime unless on presentment by a grand jury, except in cases arising in the land or naval forces, or in the militia, when in actual service in time of war or public danger, nor be deprived of life, liberty, or property without due process of law.” And the sixth guarantees the right of trial by jury, in such manner and with such regulations that, with upright judges, impartial juries, and an able bar, the innocent will be saved and the guilty punished. It is in these words: “In all criminal prosecutions the accused shall enjoy the right to a speedy and public trial by an impartial jury of the state and district wherein the crime shall have been committed, which district shall have been previously ascertained by law, and to be informed of the nature and cause of the accusation, to be confronted with the witnesses against him, to have compulsory process for obtaining witnesses in his favor, and to have the assistance of counsel for his defense.” These securities for personal liberty thus embodied were such as wisdom and experience had demonstrated to be necessary for the protection of those accused of crime. And so strong was the sense of the country of their importance, and so jealous were the people that these rights, highly prized, might be denied them by implication, that, when the original Constitution was proposed for adoption, it encountered severe opposition, and, but for the belief that it would be so amended as to embrace them, it would never have been ratified.

Time has proven the discernment of our ancestors. . . . Those great and good men foresaw that troublous times would arise when rulers and people would become restive under restraint, and seek by sharp and decisive measures to accomplish ends deemed just and proper, and that the principles of constitutional liberty would be in peril unless established by irrepealable law. The history of the world had taught them that what was done in the past might be attempted in the future. The Constitution of the United States is a law for rulers and people, equally in war and in peace, and covers with the shield of its protection all classes of men, at all times and under all circumstances. No doctrine involving more pernicious consequences was ever invented by the wit of man than that any of its provisions can be suspended during any of the great exigencies of government. Such a doctrine leads directly to anarchy or despotism, but the theory of necessity on which it is based is false, for the government, within the Constitution, has all the powers granted to it which are necessary to preserve its existence, as has been happily proved by the result of the great effort to throw off its just authority.

Have any of the rights guaranteed by the Constitution been violated in the case of Milligan? . . . [I]f so, what are they?

Every trial involves the exercise of judicial power, and from what source did the military commission that tried him derive their authority? Certainly no part of judicial power of the country was conferred on them, because the Constitution expressly vests it “in one supreme court and such inferior courts as the Congress may from time to time ordain and establish,”^[1] and it is not pretended that the commission was a court ordained and established by Congress. They cannot justify on the mandate of the President, because he is controlled by law, and has his appropriate sphere of duty, which is to execute, not to make, the laws, and there is “no unwritten criminal code to which resort can be had as a source of jurisdiction.”

But it is said that the jurisdiction is complete under the “laws and usages of war.”

It can serve no useful purpose to inquire what those laws and usages are, whence they originated, where found, and on whom they operate; they can never be applied to citizens in states which have upheld the authority of the government, and where the courts are open and their process unobstructed. This court has judicial knowledge that, in Indiana, the Federal authority was always unopposed, and its courts always open to hear criminal accusations and redress grievances, and no usage of war could sanction a military trial there for any offence whatever of a citizen in civil life in nowise connected with the military service. Congress could grant no such power, and, to the honor of our national legislature be it said, it has never been provoked by the state of the country even to attempt its exercise. One of the plainest constitutional provisions was therefore infringed when Milligan was tried by a court not ordained and established by Congress, and not composed of judges appointed during good behavior.

Why was he not delivered to the Circuit Court of Indiana to be proceeded against according to law? No reason of necessity could be urged against it, because Congress had declared penalties against the offenses charged, provided for their punishment, and directed that court to hear and determine them. And soon after this military tribunal was ended, the Circuit Court met, peacefully transacted its business, and adjourned. It needed no bayonets to protect it, and required no military aid to execute its judgments. It was held in a state, eminently distinguished for patriotism, by judges commissioned during the Rebellion, who were provided with juries, upright, intelligent, and selected by a marshal appointed by the President. The government had no right to conclude that Milligan, if guilty, would not receive in that court merited punishment, for its records disclose that it was constantly engaged in the trial of similar offenses, and was never interrupted in its administration of criminal justice. If it was dangerous, in the distracted condition of affairs, to leave Milligan unrestrained of his liberty because he “conspired against the government, afforded aid and comfort to rebels, and incited the people to insurrection,” the law said arrest him, confine him closely, render him powerless to do further mischief, and then present his case to the grand jury of the district, with proofs of his guilt, and, if indicted, try him according to the course of the common law. If this had been done, the Constitution would have been vindicated, the law of 1863 enforced, and the securities for personal liberty preserved and defended.

Another guarantee of freedom was broken when Milligan was denied a trial by jury. . . . The sixth amendment affirms that “in all criminal prosecutions the accused shall enjoy the right to a speedy and public trial by an impartial jury,” language broad enough to embrace all persons and cases; but the fifth, recognizing the necessity of an indictment or presentment before anyone can be held to answer for high crimes, “excepts cases arising in the land or naval forces, or in the militia, when in actual service, in time of war or public danger,” and the framers of the Constitution doubtless meant to limit the right of trial by jury in the sixth amendment to those persons who were subject to indictment or presentment in the fifth.

The discipline necessary to the efficiency of the army and navy required other and swifter modes of trial than are furnished by the common law courts, and, in pursuance of the power conferred by the Constitution, Congress has declared the kinds of trial, and the manner in which they shall be conducted, for offenses committed while the party is in the military or naval service. Everyone connected with these branches of the public service is amenable to the jurisdiction which Congress has created for their government, and, while thus serving, surrenders his right to be tried by the civil courts. All other persons, citizens of states where the courts are open, if charged with crime, are guaranteed the inestimable privilege of trial by jury. This privilege is a vital principle, underlying the whole administration of criminal justice. . . . In no other way can we transmit to posterity unimpaired the blessings of liberty, consecrated by the sacrifices of the Revolution.

It is claimed that martial law covers with its broad mantle the proceedings of this military commission. The proposition is this: that, in a time of war, the commander of an armed force (if, in his opinion, the exigencies of the country demand it, and of which he is to judge) has the power, within the lines of his military district, to suspend all civil rights and their remedies and subject citizens as well as soldiers to the rule of his will, and in the exercise of his lawful authority, cannot be restrained except by his superior officer or the President of the United States. . . .

The statement of this proposition shows its importance, for, if true, republican government is a failure, and there is an end of liberty regulated by law. Martial law established on such a basis destroys every guarantee of the Constitution, and effectually renders the “military independent of and superior to the civil power”—the attempt to do which by the King of Great Britain was deemed by our fathers such an offense that they assigned it to the world as one of the causes which impelled them to declare their independence. Civil liberty and this kind of martial law cannot endure together; the antagonism is irreconcilable, and, in the conflict, one or the other must perish.

This nation, as experience has proved, cannot always remain at peace, and has no right to expect that it will always have wise and humane rulers sincerely attached to the principles of the Constitution. Wicked men, ambitious of power, with hatred of liberty and contempt of law, may fill the place once occupied by Washington and Lincoln, and if this right is conceded, and the calamities of war again befall us, the dangers to human liberty are frightful to contemplate. If our fathers had failed to provide for just such a contingency, they would have been false to the trust reposed in them. They knew—the history of the world told them—the nation they were founding, be its existence short or long, would be involved in war; how often or how long continued human foresight could not tell, and that unlimited power, wherever lodged at such a time, was especially hazardous to freemen. For this, and other equally weighty reasons, they secured the inheritance they had fought to maintain by incorporating in a written constitution the safeguards which time had proved were essential to its preservation. Not one of these safeguards can the President or Congress or the Judiciary disturb, except the one concerning the writ of habeas corpus.

It is essential to the safety of every government that, in a great crisis, like the one we have just passed through, there should be a power somewhere of suspending the writ of habeas corpus. . . . The Constitution goes no further. It does not say, after a writ of habeas corpus is denied a citizen, that he shall be tried otherwise than by the course of the common law; if it had intended this result, it was easy, by the use of direct words, to have accomplished it. The illustrious men who framed that instrument were guarding the foundations of civil liberty against the abuses of unlimited power; they were full of wisdom, and the lessons of history informed them that a trial by an established court, assisted by an impartial jury, was the only sure way of protecting the citizen against oppression and wrong. Knowing this, they limited the suspension to one great right, and left the rest to remain forever inviolable. But it is insisted that the safety of the country in time of war demands that this broad claim for martial law shall be sustained. If this were true, it could be well said that a country, preserved at the sacrifice of all the cardinal principles of liberty, is not worth the cost of preservation. Happily, it is not so.

It will be borne in mind that this is not a question of the power to proclaim martial law when war exists in a community and the courts and civil authorities are overthrown. . . . [But m]artial law cannot arise from a threatened  invasion. The necessity must be actual and present, the invasion real, such as effectually closes the courts and deposes the civil administration.

It is difficult to see how the safety for the country required martial law in Indiana. If any of her citizens were plotting treason, the power of arrest could secure them until the government was prepared for their trial, when the courts were open and ready to try them. It was as easy to protect witnesses before a civil as a military tribunal, and as there could be no wish to convict except on sufficient legal evidence, surely an ordained and establish[ed]  court was better able to judge of this than a military tribunal composed of gentlemen not trained to the profession of the law.

It follows from what has been said on this subject that there are occasions when martial rule can be properly applied. If, in foreign invasion or civil war, the courts are actually closed, and it is impossible to administer criminal justice according to law, then, on the theater of active military operations, where war really prevails, there is a necessity to furnish a substitute for the civil authority, thus overthrown, to preserve the safety of the army and society, and as no power is left but the military, it is allowed to govern by martial rule until the laws can have their free course. As necessity creates the rule, so it limits its duration, for, if this government is continued after the courts are reinstated, it is a gross usurpation of power. Martial rule can never exist where the courts are open and in the proper and unobstructed exercise of their jurisdiction. . . .

Chief Justice CHASE delivered the following [concurring] opinion, joined by Justices WAYNE, SWAYNE, and MILLER.

. . . [A]s we understand it, [the Court’s opinion] asserts not only that the military commission held in Indiana was not authorized by Congress, but that it was not in the power of Congress to authorize it, from which it may be thought to follow that Congress has no power to indemnify the officers who composed the commission against liability in civil courts for acting as members of it.

We cannot agree to this. . . .

We think that Congress had power, though not exercised, to authorize the military commission which was held in Indiana. . . .

Congress has the power not only to raise and support and govern armies, but to declare war. It has therefore the power to provide by law for carrying on war. This power necessarily extends to all legislation essential to the prosecution of war with vigor and success except such as interferes with the command of the forces and the conduct of campaigns. That power and duty belong to the President as commander-in-chief. Both these powers are derived from the Constitution, but neither is defined by that instrument. Their extent must be determined by their nature and by the principles of our institutions.

The power to make the necessary laws is in Congress, the power to execute in the President. Both powers imply many subordinate and auxiliary powers. Each includes all authorities essential to its due exercise. But neither can the President, in war more than in peace, intrude upon the proper authority of Congress, nor Congress upon the proper authority of the President. Both are servants of the people, whose will is expressed in the fundamental law. Congress cannot direct the conduct of campaigns, nor can the President, or any commander under him, without the sanction of Congress, institute tribunals for the trial and punishment of offenses, either of soldiers or civilians, unless in cases of a controlling necessity, which justifies what it compels, or at least insures acts of indemnity from the justice of the legislature.

We by no means assert that Congress can establish and apply the laws of war where no war has been declared or exists.

Where peace exists, the laws of peace must prevail. What we do maintain is that, when the nation is involved in war, and some portions of the country are invaded, and all are exposed to invasion, it is within the power of Congress to determine in what states or district such great and imminent public danger exists as justifies the authorization of military tribunals for the trial of crimes and offences against the discipline or security of the army or against the public safety.

In Indiana, for example, at the time of the arrest of Milligan and his co-conspirators, it is established… that the state was a military district, was the theatre of military operations, had been actually invaded, and was constantly threatened with invasion. It appears, also, that a powerful secret association, composed of citizens and others, existed within the state, under military organization, conspiring against the draft, and plotting insurrection, the liberation of the prisoners of war at various depots, the seizure of the state and national arsenals, armed cooperation with the enemy, and war against the national government.

We cannot doubt that, in such a time of public danger, Congress had power, under the Constitution, to provide for the organization of a military commission, and for trial by that commission of persons engaged in this conspiracy. The fact that the Federal courts were open was regarded by Congress as a sufficient reason for not exercising the power; but that fact could not deprive Congress of the right to exercise it. Those courts might be open and undisturbed in the execution of their functions, and yet wholly incompetent to avert threatened danger, or to punish, with adequate promptitude and certainty, the guilty conspirators.

In Indiana, the judges and officers of the courts were loyal to the government. But it might have been otherwise. In times of rebellion and civil war it may often happen, indeed, that judges and marshals will be in active sympathy with the rebels, and courts their most efficient allies….

We have no apprehension that this power, under our American system of government, in which all official authority is derived from the people, and exercised under direct responsibility to the people, is more likely to be abused than the power to regulate commerce, or the power to borrow money. And we are unwilling to give our assent by silence to expressions of opinion which seem to us calculated, though not intended, to cripple the constitutional powers of the government, and to augment the public dangers in times of invasion and rebellion.