JACOB SULLUM: Gee, if only that Obama fellow showed the concern for constitutional niceties on warmaking that George W. Bush did.

To be more precise, Obama claims Congress already declared war on ISIS, although it surely did not realize it was doing that. Thirteen years ago this week, the president notes, Congress authorized George W. Bush “to use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons.”

It is hard to see how that Authorization for Use of Military Force (AUMF) covers ISIS, which did not exist at the time and, although it used to be affiliated with Al Qaeda, has been repudiated and expelled by the latter organization. Defending Obama’s interpretation of the AUMF, former Solicitor General Walter Dellinger tells The New York Times you could “read the reference to 9/11 organizations to include all the evolving versions of radical jihadism.” Yes, you could read it that way, but not very plausibly.

In a speech last year, Obama argued that Congress should “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, or continue to grant Presidents unbound powers more suited for traditional armed conflicts between nation states.” You can’t say he didn’t warn us.

Obama has a back-up justification for the war against ISIS—or at least, the part of it that is happening in Iraq. “The 2002 Iraq AUMF would serve as an alternative statutory authority basis on which the president may rely for military action in Iraq,” the White House says. “Even so, our position on the 2002 AUMF hasn’t changed and we’d like to see it repealed.”

So here is another authority that Obama says he should not have but which he is nevertheless happy to use as a rationale to avoid a constitutionally required vote by Congress. Nor is that the only awkward part.

With the Obama presidency, it’s awkward parts all the way down.