IN JUNE of 1863, Abraham Lincoln wrote a letter to Erasmus Corning, who had sent him the resolutions of the Albany Democratic convention censuring the Lincoln administration for what it called unconstitutional acts, such as military arrests of civilians in the North. This letter remains the best articulation of the problems that a democratic republic faces when confronted by a crisis that threatens the very existence of that republic.

The essence of Lincoln’s argument was that certain actions that are unconstitutional in the absence of rebellion or invasion become constitutional when those conditions exists–in other words, “that the Constitution is not in its application in all respects the same in cases of rebellion or invasion involving the public safety, as it is in times of profound peace and public security.”