However, April 27, 1861, President Lincoln, as an emergency measure in the face of armed insurrection and the absence of Congress, lawfully suspended (the privilege of the) writ of habeas corpus by proclamation directed to Lt. General Scott.
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No, you are confused. The letter of April 27, 1861 granted "authorization" to suspend upon meeting resistance, but Lincoln did not suspend anything. By letter of May 28, 1861, the day after Taney issued his ruling as an in-chambers opinion of the Chief Justice of the U.S. Supreme Court, Cadwalader was told by Assistant Adjutant General Townsend that he was authorized to suspend the writ.
As the official record documents demonstrate, General Keim directed Colonel Yohe to effect the arrest and Colonel Yohe directed Captain Heckman to make the arrest. General Keim was in Pennsylvania and could not be authorized to suspend habeas corpus in Maryland.
As CJ Taney accurately described it, "As the case comes before me therefore I understand that the President not only claims the right to suspend the writ of habeas corpus himself at his discretion but to delegate that discretionary power to a military officer, and to leave it to him to determine whether he will or will not obey judicial process that may be served upon him."
http://www.ehistory.com/uscw/library/or/107/0337.cfm
Page 337 Chapter LXIII. CORRESPONDENCE, ETC. - UNION.
HEADQUARTERS OF THE ARMY,
Washington, April 27, 1861.
The undersigned, General-in-Chief, of the Army, has received from the President of the United States the following communication:
COMMANDING GENERAL ARMY OF THE UNITED STATES:
You are engaged in repressing an insurrection against the laws of the United States. If at any point on or in the vicinity of the military line which is now used between the city of Philadelphia, via Perryville, Annapolis City, and Annapolis Junction, you find resistance which renders it necessary to suspend the writ of habeas corpus for the public safety, you personally, or through the officer in command at the point where resistance occurs, are authorized to suspend that writ.
ABRAHAM LINCOLN.
In accordance with the foregoing warrant, the undersigned devolves on Major-General Patterson, commanding the Department of Pennsylvania, Delaware, and Maryland; Brigadier-General Butler, commanding the Department of Annapolis, and Colonel Mansfield, commanding the Washington Department, a like authority, each within the limits of his command to execute in all proper cases the instructions of the President.
WINFIELD SCOTT.
HEADQUARTERS OF THE ARMY,
Washington, May 28, 1861.
Bvt. Major General G. CADWALADER, U. S. Army,
Commanding Department of Annapolis, Baltimore, Md.
GENERAL: Your letter of the 27th instant with inclosures reporting the arrest of John Merryman and the issue by Chief Justice Taney of a writ of habeas corpus in his case has been received.
The general-in-chief directs me to say under authority conferred upon him by the President of the United States and fully transferred to you that you will hold in secure confinement all persons implicated in treasonable practices unless you should become satisfied that the arrest in any particular case was made without sufficient evidence of guilt.
In returns to writs of habeas corpus by whomsoever issued you will most respectfully decline for the time to produce the prisoners but will say that when the present unhappy difficulties are at an end you will duly respond to the writs in question.
I am, sir, very respectfully, your obedient servant,
E. D. TOWNSEND,
Assistant Adjutant-General.
The quote being responded to is incorrectly attributed to N-S, and should have been cr.