On September 15, 1863, Lincoln imposed Congressionally authorized martial law. The authorizing act allowed the President to suspend habeas corpus through out the entire United States. Lincoln imposed the suspension on "prisoners of war, spies, or aiders and abettors of the enemy," as well as on other classes of people, such as draft dodgers. The President's proclamation was challenged in ex parte Milligan (71 US 2 ). The Supreme Court ruled that Lincoln's imposition of martial law (by way of suspension of habeas corpus) was unconstitutional.
In arguments before the Court, the counsel for the United States spoke to the question of "what is martial law?" "Martial law," it was argued, "is the will of the commanding officer of an armed force, or of a geographical military department, expressed in time of war within the limits of his military jurisdiction, as necessity demands and prudence dictates, restrained or enlarged by the orders of his military chief, or supreme executive ruler." In other words, martial law is imposed by a local commander on the region he controls, on an as-needed basis. Further, it was argued, "The officer executing martial law is at the same time supreme legislator, supreme judge, and supreme executive. As necessity makes his will the law, he only can define and declare it; and whether or not it is infringed, and of the extent of the infraction, he alone can judge; and his sole order punishes or acquits the alleged offender."
In this case, Lambden Milligan, for whom the case is named, was arrested in Indiana as a Confederate sympathizer. Indiana, like the rest of the United States, was part of a military district set up to help conduct the war. Milligan was tried by military commission and sentenced to die by hanging. After his conviction, Milligan petitioned the Circuit Court for habeas corpus, arguing that his arrest, trial, and conviction were all unconstitutional. What the Supreme Court had to decide, it said, was "Had [the military commission] the legal power and authority to try and punish [Milligan]?"
Resoundingly, the Court said no. The Court stated what is almost painfully obvious: "Martial law ... destroys every guarantee of the Constitution." The Court reminded the reader that such actions were taken by the King of Great Britain, which caused, in part, the Revolution. "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."
Did this mean that martial law could never be implemented? No, the Court said. The President can declare martial law when circumstances warrant it: When the civil authority cannot operate, then martial law is not only constitutional, but would be necessary: "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 theatre 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. It is also confined to the locality of actual war."
Because of this connection of the two concepts, it is often argued that only Congress can declare martial law, because Congress alone is granted the power to suspend the writ. The President, however, is commander-in-chief of the military, and it has been argued that the President can take it upon himself to declare martial law. In these times, Congress may decide not to act, effectively accepting martial law by failing to stop it; Congress may agree to the declaration, putting the official stamp of approval on the declaration; or it can reject the President's imposition of martial law, which could set up a power struggle between the Congress and the Executive that only the Judiciary would be able to resolve.
I get the impression that you want to believe this idiot even though you can see from the clear language of the Act that he is lying to you.
Don't trust liars. They mean you no good.