"Remember the words of James Madison: 'The Constitution supposes, what the History of all Governments demonstrates, that the Executive is the branch of power most interested in war, and most prone to it. It has accordingly with studied care vested the question of war in the Legislature.' The 'studied care' Madison describes behind that 'vesting' has not been matched by any equal and opposite studied care in recent decades, as we've divested that same power. It's not a conspiracy. Rational political actors, acting rationally to achieve rational (if sometimes dumb) political goals, have attacked and undermined our constitutional inheritance from men like Madison. For the most part, though, they've not done it to fundamentally alter the country's course but just to get around understandably frustrating impediments to their political goals. The ropes we had used to lash down presidential war-making capacity, bindings that by design made it hard for an American president to use military force without the nation's full and considered buy-in, have been hacked at with very little appreciation about why they were put there in the first place.
"When Ronald Reagan extricated himself from the Iran-Contra scandal by cutting one of those crucial mooring lines-without considered forethought or specific course headings in mind-it set the country adrift and heading into a dangerous tide.
"Congress has never since effectively asserted itself to stop a president with a bead on war. It was true of George Herbert Walker Bush. It was true of Bill Clinton. And by September 11, 2001, even if there had been real resistance to Vice President Cheney and President George W. Bush starting the next war (or two), there were no institutional barriers strong enough to have realistically stopped them. By 9/11, the war-making authority in the United States had become, for all intents and purposes, uncontested and unilateral: one man's decision to make.
"It wasn't supposed to be like this." (>>)