What about the argument that Congress has always gone along with this in the past? I mean it isn't quite that stark, but the last president that actually asked

What about the argument that Congress has always gone along with this in the past? I mean it isn't quite that stark, but the last president that actually asked congress for and got a declaration of war was Roosevelt. The last president that asked for and got permission for the use of military force was George Bush (junior) after 9/11 (obv. he meant against the Taliban). Which means all US conflicts are "based on" George Bush's approval for use of military force, about 1 per presidential term: military intervention in Lybia, the campaign against ISIS, campaign against Syria and Iraq militias/continuation against ISIS, and now Iran. Iran is a different scale I guess, but ...