From the NYT:
In the years since the Sept. 11, 2001, attacks, Congress has consistently shied away from clawing back some of its authority on matters of war and peace, despite lawmakers’ perennial bouts of outrage when presidents take military action without consulting them and long-simmering debates over the scope of presidential war powers.
I don’t think the reluctance of Congress to claw back its authority control the use of military force started with September 11. Presidents have become increasingly used to calling military strikes whenever they want since at least the cold war, and for the most part Congress has let them. The War Powers Act is an exception and dates from the brief period when Congress wanted to prevent another Vietnam. But the WPA has proved to be completely ineffectual. Just as presidents learned they could ignore the Constitutional provision vesting the power to declare war with Congress by ordering participation in undeclared conflicts without any consequences, since the 1970s they have learned there are no real consequences to violating the War Powers Act. Courts don’t feel they can order the President to not use military force, so effectively the WPA is toothless.
What it needs is some teeth. What if the WPA was amended so that if the President doesn’t follow its notice and authorization requirements, the Defense budget would automatically be slashed by 50%. No court approval would be necessary, the money to fund the war would just disappear. Of course if the public was pro-conflict there would be a lot of pressure for Congress to restore the cut money, but that vote restore the money would effectively be the consultation with Congress that the Constitutionand WPA require.