See 692 by Walt quoting CJ Rehnquist:
Lincoln felt that the great task of his Administration was to preserve the Union. If he could do it by following the Constitution, he would; but if he had to choose between preserving the Union and obeying the Constitution, he would quite willingly choose the former course.
Lincoln (and his administration) most certainly did preserve the Union. When it came to choosing between preserving the Union and obeying the Constitution, Lincoln preserved the Union.
Fair-minded people can differ over whether those acts considered necessary to preserve the Union, but which failed to obey the Constitution, were acts of greatness or not.
I have not characterized them one way or the other except to assert certain acts violated the law. Whether one considers such acts justified, under the circumstances, is another question.
To directly address your question, I did not make the point that the administration acted illegally when it arrested Milligan. It most certainly acted illegally when it subjected him, as a civilian, to a military tribunal while the civilian courts were open and functioning.
In addition to violating the Constitution, the administration violated just about every requirement of the Congressional Act under which it acted as well. The four concurring Supreme Court justices reached their conclusion on this basis.
The Administration most certainly knew, or should have known, that it was in violation of the clear and explicit requirements of the Act of Congress under which it proceeded.
The four concurring justices explained it as follows:
The CHIEF JUSTICE delivered the following opinion.
Four members of the court, concurring with their brethren in the order heretofore made in this cause, but unable to concur in some important particulares with the opinion which has just been read, think it their duty to make a separate statement of their views of the whole case.
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The trial and sentence of Milligan were by military commission convened in Indiana during the fall of 1864. The action of the commission had been under consideration by President Lincoln for some time, when he himself became the victim of an abhorred conspiracy. It was approved by his successor in May, 1865, and the sentence was ordered to be carried into execution.
The proceedings, therefore, had the fullest sanction of the executive department of the government. This sanction requires the most respectful and the most careful consideration of this court. The sentence which it supports must not be set aside except upon the clearest conviction that it cannot be reconciled with the Constitution and the constitutional legislation of Congress.
We must inquire, then, what constitutional or statutory provisions have relation to this military proceeding.
The act of Congress of March 3d, 1863, comprises all the legislation which seems to require consideration in this connection.
The constitutionality of this act has not been questioned and is not doubted.
The first section authorized the suspension, during the Rebellion, of the writ of habeas corpus throughout the United States by the President. The two next sections limited this authority in important respects.
The second section required that lists of all persons, being citizens of states in which the administration of the laws had continued unimpaired in the Federal courts, who were then held or might thereafter be held as prisoners of the United States, under the authority of the President, otherwise than as prisoners of war, should be furnished to the judges of the Circuit and District Courts. The lists transmitted to the judges were to contain the names of all persons, residing within their respective jurisdictions, charged with violation of national law. And it was required, in cases where the grand jury in attendance upon any of these courts should terminate its session without proceeding by indictment or otherwise against any prisoner named in the list, that the judge of the court should forthwith make an order that such prisoner desiring a discharge, should be brought before him or the court to be discharged, on entering into recognizance, if required, to keep the peace and for good behavior, or to appear, as the court might direct, to be further dealt with according to law. Every officer of the United States having custody of such prisoners was required to obey and execute the judge's order, under penalty, for refusal or delay, of fine and imprisonment.
The third section provided, in case lists of persons other than prisoners of war then held in confinement, or thereafter arrested, should not be furnished within twenty days after the passage of the act, or, in cases of subsequent arrest, within twenty days after the time of arrest, that any citizen, after the termination of a session of the grand jury without indictment or presentment, might, by petition alleging the facts and verified by oath, obtain the judge's order of discharge in favor of any person so imprisoned, on the terms and conditions prescribed in the second section.
It was made the duty of the District Attorney of the United States to attend examinations on petitions for discharge.
It was under this act that Milligan petitioned the Circuit Court for the District of Indiana for discharge from imprisonment.
The holding of the Circuit and District Courts of the United States in Indiana had been uninterrupted. The administration of the laws in the Federal courts had remained unimpaired. Milligan was imprisoned under the authority of the President, and was not a prisoner of war. No list of prisoners had been furnished to the judges, either of the District or Circuit Courts, as required by the law. A grand jury had attended the Circuit Courts of the Indiana district, while Milligan was there imprisoned, and had closed its session without finding any indictment or presentment or otherwise proceeding against the prisoner.
His case was thus brought within the precise letter and intent of the act of Congress, unless it can be said that Milligan was not imprisoned by authority of the President; and nothing of this sort was claimed in argument on the part of the government.
It is clear upon this statement that the Circuit Court was bound to hear Milligan's petition for the writ of habeas corpus, called in the act an order to bring the prisoner before the judge or the court, and to issue the writ, or, in the language of the act, to make the order.
The first question, therefore-Ought the writ to issue?-must be answered in the affirmative. And it is equally clear that he was entitled to the discharge prayed for.
It must be borne in mind that the prayer of the petition was not for an absolute discharge, but to be delivered from military custody and imprisonment, and if found probably guilty of any offence, to be turned over to the proper tribunal for inquiry and punishment; or, if not found thus probably guilty, to be discharged altogether.
And the express terms of the act of Congress required this action of the court. The prisoner must be discharged on giving such recognizance as the court should require, not only for good behavior, but for appearance, as directed by the court, to answer and be further dealt with according to law.
The first section of the act authorized the suspension of the writ of habeas corpus generally throughout the United States. The second and third sections limited this suspension, in certain cases, within states where the administration of justice by the Federal courts remained unimpaired. In these cases the writ was still to issue, and under it the prisoner was entitled to his discharge by a circuit or district judge or court, unless held to bail for appearance to answer charges. No other judge or court could make an order of discharge under the writ. Except under the circumstances pointed out by the act, neither circuit nor district judge or court could make such an order. But under those circumstances the writ must be issued, and the relief from imprisonment directed by the act must be afforded. The commands of the act were positive, and left no discretion to court or judge.
An affirmative answer must, therefore, be given to the second question, namely: Ought Milligan to be discharged according to the prayer of the petition?
That the third question, namely: Had the military commission in Indiana, under the facts stated, jurisdiction to try and sentence Milligan? must be answered negatively is an unavoidable inference from affirmative answers to the other two.
The military commission could not have jurisdiction to try and sentence Milligan, if he could not be detained in prison under his original arrest or under sentence, after the close of a session of the grand jury without indictment or other proceeding against him.
Indeed, the act seems to have been framed on purpose to secure the trial of all offences of citizens by civil tribunals, in states where these tribunals were not interrupted in the regular exercise of their functions.
Under it, in such states, the privilege of the writ might be suspended. Any person regarded as dangerous to the public safety might be arrested and detained until after the session of a grand jury. Until after such session no person arrested could have the benefit of the writ; and even then no such person could be discharged except on such terms, as to future appearance, as the court might impose. These provisions obviously contemplate no other trial or sentence than that of a civil court, and we could not assert the legality of a trial and sentence by a military commission, under the circumstances specified in the act and described in the petition, without disregarding the plain directions of Congress.
We agree, therefore, that the first two questions certified must receive affirmative answers, and the last a negative. We do not doubt that the positive provisions of the act of Congress require such answers. We do not think it necessary to look beyond these provisions. In them we find sufficient and controlling reasons for our conclusions.
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In retrospect that is true, the Supreme Court ruled as such. But is it your contention that the Lincoln administration knew that they were acting illegally when habeas corpus was suspended and military courts operated in states like Indiana?