If the latter sounds vaguely familiar it should. As Scott Horton reminds, it was the reasoning used by Nazi legal theorist Carl Schmitt to justify the end of the Weimar Republic.
What exactly did Kennedy mean by referring to a Constitution that can be “switched on and off at will”? In presenting the opposing viewpoint this way he was taking dead aim at the notion of a state of exception which underlies the whole architecture of Bush war on terror policies. Simply put, these policies argue that while the Executive is limited by the checks and balances of the American constitution during peacetime and at home, all those shackles fall away when war erupts and when he acts outside the nation’s territory. This viewpoint has limited historical precedents, but no Administration has pressed it quite so fiercely as that of George W. Bush.
Moreover the true roots of this notion lie in the thinking of a troubling figure, Carl Schmitt. The most important conservative legal thinker on the European continent between the wars, Schmitt felt that modern liberal democracy crafted on the Anglo-American model was too weak to cope with the social and political shockwaves that racked Europe between the wars. He suggested that these liberal democratic constitutions all had an “escape hatch,” namely a clause which would allow the Executive to set aside the array of civil liberties which formed the constitution’s foundation whenever the state found itself engulfed in an existential threat. Exactly what this “state of exception” was and how it could be triggered would depend on the peculiarities of each constitution.
For the past seven years, Americans have witnessed an effort to engineer a “state of exception” to the American constitution. Its key element has been a new definition of war—the “war on terror”–which has neither territorial nor temporal boundaries ....
... It was designed to bolster an assertion of unprecedented executive power, a reshuffling of the political cards at home. The executive was to emerge as the paramount power in the nation’s government, relegating the other branches to the status of constitutional hood ornaments. The Republican Party was to be anchored in to a generation of rule.