Ok, let's see if this breaks through....
"The United States is at war—and has been, continuously, for ten years. This is a reality, of course. But more than that, it is a legality. Legally—constitutionally—the United States has been in a condition of declared war for ten years.
On September 18, 2001, Congress enacted into law, and President George W. Bush signed, what is arguably the broadest declaration of war in our nation’s history. “Whereas on September 11, 2001, acts of treacherous violence were committed against the United States,” begins the Authorization for Use of Military Force (AUMF),
Constitutionally, the 9-18-01 Act is a Declaration of War. Congress, not the President, has the power “to declare war,” the result of a deliberate decision by the framers of the Constitution to transfer the traditional war-initiating executive power of a king to a representative, republican legislature. The President, the framers determined, should have only the power to counter attacks on the nation—to repel and respond—but not to initiate war on his own.
The President, as Commander-in-Chief, would have complete military authority to conduct war, once declared: he, and not Congress, makes the decisions as to how to wage war, including all matters of military engagement, strategy, tactics, rules of engagement, diplomacy, armistice, foreign relations with allies and adversaries, and policies toward captured enemies (including detention, interrogation, and military punishment—the subjects of so much friction in recent years). The framers’ division was clear: Congress declares wars; the President fights and concludes them.
Congress’s power to declare war does not require the use of magic words. Congress need not say “declare” and it need not say “war,” and there may be practical and diplomatic reasons to couch a war declaration in terms more congenial to the regime of “international law,” which favors the language of individual and collective self-defense over the old-fashioned, indecorous language of war. But war it is. More to the point, constitutionally, the 9-18-01 Authorization for Use of Military Force is an exercise of Congress’s legislative power “to declare war.”
The AUMF is remarkable, even stunning, in its sweep.
It accounts for and justifies nearly every military action in which the United States has engaged in the past ten years in fighting the war on terror. (Iraq was the subject of a separate, overlapping war-authorization. U.S. military action in Libya, as I will discuss, is not justified by the AUMF and is probably best classified as an unconstitutional war.)"
Declaration of War: Ten Years Later | Public Discourse
So, "Bush's wars" were constitutional, and Obama's war was not.