In a conversation with a colleague the subject of US War Making Powers was brought up. He insisted that the President is allowed to wage war for 90 days without congressional approval (because of what he heard in a movie) while I insisted it was Congress' authority alone. Well, I did some research and here is what I found. 50 USC §§ 1541-1548 is the "War Powers Resolution" adopted in 1973 over Nixon's veto. It provides a requirement upon the President to provide a report to Congress within 48 hours after deploying US Forces. Congress may immediately vote to cease the deployment, and it may not continue after 60 days without express approval.
The more pressing issue in my mind is what the Constitution actually says. Article 1 § 8 line 11 gives Congress alone the authority to declare war. Lines 12-13 allow for a temporary army, and a permanent Navy. Article 2 states the authority of the President and nowhere do you find the word 'war.'
In a society based upon a constitution there can be no laws that circumvent that document. Either the constitution is of no effect, or the new law is. I see no room for middle ground. Obviously no Congress or President in living memory has chosen to abide by the Constitution, sadly not even the Gipper changed that much.