After waging war on the Islamic State in Iraq and Syria (ISIS) for six months, President Obama is asking Congress for its blessing. But whether or not he gets it, he plans to continue doing whatever he thinks is necessary to "degrade and ultimately destroy this terrorist group."

Since he will not take no for an answer, Obama's solicitation of the legislative branch's input is a gesture of contempt rather than respect. Congress should assert its constitutional authority by rescinding the 2001 authorization for use of military force (AUMF) that Obama implausibly claims already gives him permission for his war on ISIS.

The 2001 AUMF authorized military action against the perpetrators of the 9/11 terrorist attacks. In a 2013 speech, Obama called upon Congress to "refine, and ultimately repeal, the AUMF's mandate," because "unless we discipline our thinking, our definitions, our actions, we may be drawn into more wars we don't need to fight."

Last year Obama illustrated that danger by citing the 2001 AUMF as a justification for the military campaign against ISIS, which did not exist in 2001 and is no longer part of Al Qaeda. The ISIS-specific AUMF that he proposed last week repeals the 2002 resolution authorizing George W. Bush's war in Iraq but conspicuously leaves in place the 2001 AUMF.

Given Obama's reading of the post-9/11 resolution, the details of the new AUMF ultimately do not matter, but they do illustrate the president's bad faith. The proposed resolution authorizes military action "against ISIL [another name for ISIS] or associated persons or forces" anywhere in the world, a broad mandate that could easily lead to a proliferation of enemies and battlefields.

The "limitations" included in Obama's AUMF have no teeth. One says the AUMF "does not authorize the use of the United States Armed Forces in enduring offensive ground combat operations." It's anybody's guess what "enduring" means.

Obama says the resolution "is not the authorization of another ground war like Afghanistan or Iraq," so maybe anything short of a dozen or so years does not count as "enduring" as far as he is concerned. Remember: This is the same president who claimed that dropping bombs on Libya did not constitute "hostilities."

The proposed AUMF also includes a time limit: It expires after three years "unless reauthorized." If that were a problem, it would be the next president's, not Obama's. But since by Obama's account the resolution does not give him any authority he does not already have under the 2001 AUMF (which has no expiration date), the three-year limit is no limit at all.

"I do not believe America's interests are served by endless war, or by remaining on a perpetual war footing," Obama said last week, explaining the three-year limit and the proposed repeal of the Iraq war resolution. Two years ago, he made the same argument in explaining the need to scrap the 2001 AUMF, saying it was time to "determine how we can continue to fight terrorism without keeping America on a perpetual wartime footing."

Congress should take Obama at his word by repealing the 2001 resolution. If legislators believe ISIS "poses a grave threat" to "the national security interests of the United States," as the president claims, they can approve a new resolution authorizing the war the president is already waging, ideally with a narrower definition of the enemy and a clearer understanding of the goal.

I am not convinced ISIS poses the sort of threat that justifies war. But under the Constitution, Congress is supposed to make that call. By relying on a mandate that he himself says is outdated and dangerously broad, Obama has avoided the need to make the case for war, and Congress has let him, afraid to share responsibility for a military campaign that may end disastrously.

Last week Senate Majority Leader Mitch McConnell (R-Ky.) said "Congress must meet its responsibility to decide whether our military should use force." Better late than never.

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