A key question in Wednesday’s Senate Foreign Relations Committee hearing involved what the administration means by ISIL’s “associated forces,” and how the President’s proposed force authorization might permit this or the next administration to send combat forces to fight ISIL affiliates in Libya, Nigeria, and other corners of the globe.

In an essay in Foreign Policy and a more recent post, I identified the potential slippery slope toward an ever-expanding war against ISIL’s purported affiliates. Statements by administration officials in yesterday’s hearings unfortunately added to those concerns.

The key provision in the President’s recently proposed authorization for the use of military force (AUMF) says:

SEC. 5. ASSOCIATED PERSONS OR FORCES DEFINED. In this joint resolution, the term ‘‘associated persons or forces’’ means individuals and organizations fighting for, on behalf of, or alongside ISIL or any closely-related successor entity in hostilities against the United States or its coalition partners.

Two worrisome points about that provision stand out in light of Wednesday’s hearings:

1. The slippery slope of “associated forces”

I argued in the Foreign Policy essay that the definition of associated forces in the White House’s proposed AUMF is unusually expansive — compared in part to the 2001 AUMF as a baseline. Marty Lederman has also raised excellent questions about the lack of a co-belligerency element in the administration’s draft definition, and Nathalie Weizmann has explained what a co-belligerency test might entail. (See also question no. 4 in Jack Goldsmith, Steve Vladeck, and my post, “Six Questions Congress Should Ask the Administration about its ISIL AUMF.”)

So what happened at the Senate Committee hearings to deepen my concerns about a slippery slope?

In answer to a question by Sen. Ed Markey (D-Mass.), Defense Secretary Ashton Carter stated:

“But you do see in this social media-fueled movement called ISIL, people who are wannabes or want to join or have been associated with al-Qaeda or some other group who are putting up the flag of ISIL. And we need to recognize that that’s a characteristic of the campaign and that’s why the AUMF has the language that it does.” (Emphasis added.)

Is that right? A group just wanting to associate itself with ISIL or professing allegiance, and they would come under the authorization for military force? Surely there should be some form of direct association or linkage — at a minimum, something like a co-belligerency test or a formal coalition.

As President Obama said a year ago in the context of describing al-Qaeda and its potential associates, “if a jayvee team puts on Lakers uniforms that doesn’t make them Kobe Bryant.’” So what about Carter’s ISIL “wannabes”?

Was the Defense Secretary being precise in his language, and would he choose to say it differently next time? He might have meant exactly what he said and represented the Administration’s point of view accurately. After all, Carter’s response to Sen. Markey was consistent with a statement by anonymous U.S. officials that I highlighted once before. As reported in February by the New York Times: “[The President’s draft AUMF] could also be used to address future threats from small bands of violent Islamist militants in Libya, Yemen and other Middle Eastern and North African countries that have ‘rebranded’ their identities to take the Islamic State name, and benefit from its notoriety, American officials said.”

It must be added that the Defense Secretary, in an earlier exchange with Sen. Bob. Menendez (D-NJ), made crystal clear that a second requirement of the associated forces test is that the group must “also have the intent of threatening Americans” (one should add: or American coalition partners). But even with that second prong, it would be an exceedingly broad license were the force authorization to sweep in groups that (a) rebrand themselves as ISIL and (b) direct hostilities against the United States. The missing element here is still something like the co-belligerency test.

Later in the hearings, Secretary of State John Kerry also added a statement about the associated forces language. But all Kerry technically did was to reiterate that such an affiliated group would need to direct its hostilities against the United States or our coalition forces. He stated:

“[M]erely by pledging or flying the flag, or saying that they’re now affiliated, there’s no decision made nor any contemplated that they would be covered under this moment. That’s not adequate. But if, as Secretary Carter said, they start to attack the United States or join with ISIL in a specific strategy to attack coalition partners, that would raise a legitimate question and this authorization could in fact, under those circumstances, cover them. It would have to be, you know, there [would be] a lot of internal scrubbing of exactly what those activities were, what the implications are and so forth. It would not be automatic, but it would be open to judgment.” (Emphasis added.)

That said, Mr. Kerry did refer to the affiliate “join[ing] with ISIL in a specific strategy to attack coalition partners” as part of the framework, and one would presume that standard also applies to actions against the United States. Still, Kerry did not, by any stretch, stipulate that phrase is an essential requirement of the test of associated forces. Indeed, it is likely not a minimum condition of the test since to “join … a specific strategy to attack” is likely too high a threshold than the administration would even apply to al-Qaeda under the existing co-belligerency standard. Kerry was more likely using the phrase by way of example–not setting an outer limit.

2. The slippery concept of “successor entities”

While some of the senators honed in on the administration’s definition of “associated forces,” they did not tackle the entirely separate category of ISIL’s successor entities. This is especially remarkable since several of the Senators have been incredulous about the administration’s notion of successor entities as applied to the 2001 AUMF. As I explained in the essay in Foreign Policy, by writing the successor entity theory into the draft ISIL AUMF, “the president is asking Congress to endorse his theory that looped in the Islamic State under the 2001 AUMF as a ‘successor’ to al Qaeda.” In other words, the administration wants to get Congress on board with the notion of successor entities and give that concept new life in the ISIL AUMF.

What could possibly go wrong? As Harold Koh wrote in a Just Security post, such a theory involves “a dangerous methodology whereby the current and future Presidents can cite ‘factual evidence of common [al Qaeda] DNA’” to redirect US military forces against other groups far removed from the original authorization. Do members of Congress really want to go down that path—or be held responsible for it later? If they are concerned, as they should be, there is still plenty of time to raise questions.

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The issue for me is not simply how the Obama White House might apply the AUMF and the scope of this Administration’s ongoing practices. The bigger problem is the potential breadth of the language that will be left for future administrations to construe. Right now the “legislative history” that is being created in these hearings is not helpful in that regard.

At bottom, a deep problem with Wednesday’s hearings and other exchanges with the Administration is our having to read the tea leaves and the frustrating imprecision of it all. Members of Congress on future occasions need to ask more precise questions and follow-ups that can identify exactly what is on the Administration’s mind. And Administration officials should be much more precise in their answers. We need to know much better what’s in and what’s out of the range of groups against which Americans might be waging war for the foreseeable (and unforeseeable) future.