Article 1 of the Constitution establishes that "the Privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it" -- but does not specify which authority has the jurisdiction to decide on the suspension.
Another passage of Article 1 declares that the power to declare war and to raise and support the army and navy rests with Congress, BUT Article 2 states that "the President shall be Commander in Chief of the Army and Navy of the United States."
During the Civil War (1861–1865), Lincoln acted counter to the text of Article 1 (on April 15, 1861) by proclaiming that an army of seventy-five thousand men was to be raised and convened a special session of Congress for July 4. In the ten weeks that passed between April 15 and July 4, Lincoln acted de facto as a total dictator. On April 27, Lincoln authorized the General in Chief of the Army to suspend the writ of Habeas Corpus whenever he deemed it necessary along the military line between Washington and Philadelphia. Furthermore, on February 1862, Lincoln imposed censorship of the mail and authorized the arrest and detention in military prisons of persons suspected of "disloyal and treasonable practices".
In the speech he delivered to Congress July 4 1861, President Lincoln justified his actions as the holder of a supreme power to violate the Constitution in a situation of necessity:
"Whether strictly legal or not, [the measures he had adopted had been taken] under what appeared to be a popular demand and a public necessity" in the certainty that Congress would ratify them. Those exceptional measures were based on the conviction that even fundamental, natural law could be violated IF the very existence of the union and the juridical order were at stake:
"Are all the laws but one to go unexecuted, and the Government itself go to pieces lest that one be violated?"
--Lincoln
Although Congress was aware that the constitutional jurisdictions had been transgressed, it could do nothing but ratify the actions of the President, as it did on August 6, 1861. Strengthened by this approval, Lincoln proclaimed on September the emancipation of the slaves on his authority alone and later generalized the state of emergency throughout the entire territory of the United States, authorizing the arrest and trial before courts martial of "all Rebels and Insurgents, their aiders and abettors within the United States, and all persons discouraging volunteer enlistments, resisting militia drafts, or guilty of any disloyal practice, affording aid and comfort to Rebels against the authority of the United States."
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During World War One President Wilson assumed broader powers than those Lincoln had claimed. However, instead of ignoring Congress, as Lincoln had done, Wilson had those extraordinary powers delegated to him by Congress. Instead of declaring a state of emergency, he had exceptional laws issued. From 1917 to 1918, Congress approved a series of acts (from the Espionage Act of 1917 to the Departmental Reorganization Act of 1918) that granted the President COMPLETE CONTROL over the administration of the United States and not only prohibited disloyal activities (such as collaboration with the enemy and the diffusion of false reports), but even made it a crime to "willfully utter, print, write, or publish any disloyal, profane, scurrilous, or abusive language about the form of government of the United States" (from the Sedition Act of 1918).
Since the power of the President is grounded in the emergency linked to a state of war, the metaphor of war became a part of the presidential vocabulary whenever decisions considered to be of vital importance are being imposed.
In 1933, Franklin D. Roosevelt was able to assume extraordinary powers by presenting his actions as those of a Commander in Chief during a military campaign:
"I assume unhesitatingly the leadership of this great army of our people dedicated to a disciplined attack upon our common problems.…I am prepared under my constitutional duty to recommend the measures that a stricken Nation in the midst of a stricken world may require.…But in the event that the Congress shall fail to take [the necessary measures] and in the event that the national emergency is still critical, I shall not evade the clear course of duty that will then confront me. I shall ask the Congress for the one remaining instrument to meet the crisis—broad Executive power to wage war against the emergency, as great as the power that would be given to me if we were in fact invaded by a foreign foe."--Franklin D. Roosevelt, First Inaugural Address, March 4, 1933
From the constitutional point of view, the New Deal was realized by delegating to the President (through a series of statutes culminating in the National Recovery Act of June 1933) an UNLIMITED POWER to CONTROL every aspect of the economic life.
The outbreak of World War Two extended these powers with the creation of a "Office of Emergency Management" [the ancestor of today's FEMA]. On September 7, 1942, FDR renewed his claim to TOTAL CONTROL during the emergency:
On February 19, 1942, the FDR administration proceeded with the internment of seventy thousand American citizens of Japanese descent who resided on the West Coast (along with forty thousand Japanese citizens who lived and worked there).