Charlie Savage, a journalist for The New York Times, reported Thursday that the Departments of State and Defense have told Congress that they have the authority to “indefinitely keep American military forces deployed in Syria and Iraq even in territory that has been cleared of Islamic State fighters.” That authority, they say, comes from legislation passed in 2001 in the wake of the 9/11 attacks and from a separate law, signed in 2002, which authorized the use of force in Iraq. The Obama Administration first claimed in 2014 that these Authorizations for Use of Military Force – or AUMFs – covered U.S. operations against ISIS, but the government has so far eluded judicial review of that tenuous legal rationale.

But Doe v. Mattis, the habeas case of an anonymous U.S. citizen accused of being a member of ISIS, threatens to pull the legal rug out from under the government’s claim. The central question in Doe forces judicial review of the legal basis for holding an ISIS member under law-of-war detention. The answer requires cutting through what Judge Tanya Chutkan called a “bramble,” to find out whether Congress has authorized the war against ISIS.

Although Doe’s legal arguments are tailored to the detention of a U.S. citizen, wartime detention authority rests on the broader issue of the war’s congressional authorization. The government, in its redacted reply to the habeas petition, argues that wartime authority to detain ISIS members stems from three independent sources: the 2001 AUMF, the 2002 AUMF, and Article II commander-in-chief authority. In their response to the government’s merits brief,  Doe’s lawyers argue that neither the 2001 nor 2002 AUMF authorizes the fight against ISIS, nor is there Article II authority to unilaterally detain an ISIS member indefinitely. His defense team also argues that congressional appropriations for operations against ISIS are no substitute for war authorization. Meanwhile, the Trump administration argues that appropriations, or war funding, are evidence of congressional authorization.

As Just Security readers know, the saga over the legal basis for anti-ISIS operations has dragged on for years. While administrations have strained to apply existing war authorizations to ISIS, several members of Congress – from both parties – have protested the use of outdated AUMFs to cover a new conflict. But no court has ever had to confront the question.

Now that we’re facing a legal showdown over the Trump administrations’ claims, it’s helpful to revisit how we got here, why legal experts have argued that these claims rest on shaky legal ground, and what members of Congress have said over the years.

Executive Stretching of the Old AUMFs to Justify Anti-ISIS Operations

Back in 2014, when the Obama administration announced that the 2001 AUMF authorized the military campaign against ISIS, legislators and legal experts collectively scratched their heads. How could Congress, when it passed a law to fight those responsible for the 9/11 attacks, have intended to authorize the use of force against a group that had nothing to do with 9/11, and that al-Qaeda itself had disavowed?

Just a year earlier, President Barack Obama hinted that the 2001 AUMF might finally be facing its death, when he said he looked forward to engaging with Congress to repeal it. The authorization’s persistence into its twelfth year, he worried, threatened to draw us “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.” The 2002 AUMF, passed by Congress and signed into law to confront Saddam Hussein’s regime in Iraq, wasn’t an attractive legal justification for ISIS either. Shortly before the Obama administration settled on using the 2001 AUMF as justification for its anti-ISIS operations, National Security Adviser Susan Rice told Republican Speaker of the House John Boehner that “the [2002] Iraq AUMF is no longer used for any U.S. government activities.” At the same time, the National Security Council was reportedly “struggling” to find legal cover for fighting ISIS, and they weren’t confident that the existing authorizations were up to the job.

Yet here we are. It’s 2018, and multiple administrations have stretched the 60-word 2001 AUMF to authorize what Congress sought to avoid when it anchored the law to 9/11: a geographically expanding war that marches autonomously into the future. It has now been used more than three dozen times to justify the use of force in more than a dozen countries.

National Security Law Experts on Congressional Authorization for the Fight Against ISIS

At first, the Obama administration’s 2014 proclamation that the 2001 AUMF authorized the fight against ISIS “astonished” legal scholars and national security experts. The administration argued that ISIS was a successor entity of al-Qaeda in Iraq, and therefore qualified as al-Qaeda for purposes of the conflict. The only other way for ISIS to be covered would be if it were an associated force of al-Qaeda. But as commentators pointed out, ISIS was actively clashing with al-Qaeda, al-Qaeda publicly disavowed them, and ISIS did not exist at the time of the 9/11 attacks. Furthermore, “associated force” doesn’t appear in the text of either AUMF. It’s a term the Obama administration employed in order to justify the use of the 2001 AUMF to fight against groups beyond those contemplated by the law. Since then, the term has been codified in congressional statute: The 2012 National Defense Authorization Act provides for the detention of members of al-Qaeda, the Taliban, and “associated forces,” but only pursuant to the conflicts authorized by the 2001 AUMF.

In Doe, the U.S. government argues that at the time U.S. operations against ISIS began, ISIS was either part of, or an associated force of al-Qaeda. A subsequent split between the terrorist groups, the government argues, does not remove the authority to fight ISIS. In other words, even if the groups have disassociated, the relevant inquiry is whether they were associated at the time U.S. operations against them began. This reasoning reflects the government’s interpretation of the 2001 AUMF as a forward-looking resolution, rather than one tailored to responding to the 9/11 attacks. Since the Obama administration first revealed this reasoning, experts have worried that the government position is not only legally sketchy, but also practically problematic, as it threatens to make the AUMF infinitely elastic.

At the time, Robert Chesney called the Obama administration’s argument, “stunning from a legal perspective.” Ben Wittes said in September 2014 that stretching the 2001 AUMF to cover ISIS was an “extremely implausible” interpretation, and “not a stable or sustainable reading of the law.” A “remarkable consensus,” as Ryan Goodman characterized it, emerged among national security law experts “that ISIS is not covered by the 2001 AUMF.” Regardless of divergent prudential viewpoints on the issue, Goodman wrote,

“We all seem to agree that the 2001 authorization for September 11 does not give the President authority to send the U.S. military to fight ISIS.”

Jennifer Daskal and Steve Vladeck argued that we would be using permission for a war “we sought to fight a decade ago” as an “end-run around congressional authorization in response to new threats in the future.”

So what legal basis is there for the ISIS fight, then? The 2002 AUMF was no more palatable. Vladeck and Daskal summed it up one month before Obama announced his legal theory for fighting ISIS:

“Because ISIS had no connection to 9/11, it’s not a good fit for the 2001 AUMF. And because ISIS had nothing to do with Saddam Hussein’s regime in Iraq, it’s an even poorer fit for the 2002 statute.”

Goodman, Daskal and Vladeck later said that invoking the 2002 AUMF “against a different enemy, a different threat, and a different form of armed conflict—would surely violate the plain language of the 2002 AUMF.”

But some commentators have argued that it’s not outlandish to say that Congress has authorized the war on ISIS, or at least has given it tacit, ex post facto approval by funding the operations. Wittes pointed out that congressional inaction—meaning, Congress’ failure to repeal the old AUMFs or pass a new one—amounts to congressional approval of the executive branch’s interpretation. Vladeck noted that the ‘ISIS is a successor force of al-Qaeda’ argument seemed a more feasible justification for the administration’s interpretation than the ‘associated force’ argument.

Daskal, meanwhile, called the lack of congressional action “a colossal failure of our democratic processes.” “The job of our Senators and Representatives,” she continued, “is not supposed to be easy. It is not supposed to be about securing re-election. It is supposed to be about making the very difficult and complicated decisions that the Founders entrusted to them – including the decisions about when and against whom to engage in armed conflict. This is a responsibility that Congress should embrace, not shirk.”

Members of Congress on Authorization for the Fight Against ISIS

Certain lawmakers have repeatedly tried to address what they see as a lack of legal authority for the current fight against ISIS, but draft proposals have gone nowhere, and calls for a new war authorization have received all of 45 minutes’ worth of floor debate. Members of the current Congress feel they haven’t had the opportunity to authorize today’s operations against ISIS. Only a quarter of the 98 senators who voted for the 2001 AUMF are still in office and 16 are no longer alive. Of the 420 representatives who voted for it, only 20 percent are still in the House, and 41 of them have died.

Sen. Dick Durbin (D-Ill.) put this into perspective in 2013 when he said,

“None of us, not one who voted for [the 2001 AUMF], could have envisioned we were voting for the longest war in American history or that we were about to give future presidents the authority to fight terrorism as far flung as Yemen and Somalia. I don’t think any of us envisioned that possibility.”

In 2014, when Secretary of State John Kerry told the Senate Foreign Relations Committee that the Obama administration thought it had the authority to go after ISIS, under the 2001 and 2002 AUMFs, members of both parties disagreed. Sen. Jim Risch (R-Idaho) said “I do not believe [the administration] is acting within their authority, I agree with the Democrats on that.” Sen. Ben Cardin (D-Md.) voiced his disagreement “with the contention that either the 2001 or 2002 authorizations for the use of military force provide a full authorization for the current U.S. military action occurring in Iraq and Syria.”

Sen. Rand Paul (R-Ky.) demonstrated in 2016 and again in 2017 that Congress hasn’t lost interest in fulfilling its “constitutional mandate that war needs to be authorized by Congress…before troops are placed in harm’s way.” Sen. Tim Kaine (D-Va.) agreed, calling it the “height of public immorality” to “order people into harm’s way to risk their lives unless there’s a political consensus.” In 2017, a bipartisan group of 46 lawmakers wrote to House Speaker Paul Ryan (R-Wis.) requesting a debate and vote on an AUMF that defines the “purpose, nature and limits of U.S. military engagement against the Islamic State,” lamenting that “for too long, the United States has conducted military operations against the Islamic State under the justification of the outdated 2001 [AUMF].”

But some members of Congress are content to allow the executive stretching, at least as an alternative to going on record in support of, or in opposition to, a new authorization. A few lawmakers have gone further, saying that no congressional authorization is necessary. In their view, the president has inherent commander-in-chief authority to wage war without limit. When Rep. Peter King (R-N.Y.) espoused this view, his colleague Rep. Mick Mulvaney (R-S.C.) responded: “I’m pretty sure the Constitution says Congress declares war, but maybe Mr. King is reading a different Constitution than I am.”

It’s also worth noting that the members of Congress who voted for the 2001 AUMF passed a relatively narrow resolution after declining to enact the Bush Administration’s requested language, which would have been much broader. The 2001 AUMF’s legislative history suggests that members who voted for it did so understanding its scope to be narrow—limited to, as Rep. Lamar Smith (R-Texas) said, “using force only against those responsible for the terrorist attacks last Tuesday.” Rep. Diane Watson (D-Calif.) was careful to note that:

“the resolution is not a carte blanche endorsement for the use of force against any suspected terrorist group anywhere in the world, but is more narrowly crafted to endorse all necessary and appropriate use of force against nations, organizations, and persons that participated in the attacks that occurred on September 11.”

Rep. Jan Schakowsky (D-Ill.) agreed that the language was “carefully drafted to restrict our response to those we know to be responsible for this atrocity.”

Democratic Rep. Barbara Lee’s 2001 concerns about the AUMF being stretched beyond recognition are rooted in the importance of the separation of powers. What she said in 2014 remains true: Congress needs to have “a full debate and vote on any military action, as required by the Constitution. The American people deserve a public debate on all the options to dismantle ISIS, including their costs and consequences to our national security and domestic priorities.”

And it seems many members of Congress, including those who voted for the old AUMFs, feel they haven’t authorized the current fight against ISIS. Unless the executive branch prolongs the evasion of this question by transferring Doe to the custody of another country or prosecuting him in federal court, Judge Chutkan may have to step in and rule once and for all on the legality of the United States’ most recent wars.