Twelve years ago today, in the immediate aftermath of the September 11 attacks, President Bush signed the Authorization for Use of Military Force (AUMF) into law. This document, passed with virtually unanimous support in both houses of Congress, has provided the primary legal basis for the wide-ranging war on terror that the United States has waged. Its main clause authorizes the president

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, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons.

Since its passage, this law has underpinned the war in Afghanistan, the practice of indefinite detention, and the campaign of targeted killings in Pakistan, Yemen and elsewhere. Congress and the courts have interpreted the law as applying to authorize force against the Taliban, Al Qaeda and their “associated forces,” although that phrase itself does not appear in the text of the AUMF.

Now, with the American combat mission in Afghanistan scheduled to wind down at the end of next year, there is a growing chorus of voices calling for the AUMF to be narrowed or even repealed outright along with it. In March, the New York Times editorial page called for the AUMF to be repealed effective upon the U.S. withdrawal from Afghanistan. Several months later, Representative Adam Schiff introduced legislation that would have done exactly that. Saying that the 2001 law “now poorly defines those who pose a threat to our country,” Schiff argued that Congress should cut off funding for implementing the AUMF after 2014 and work with the White House to determine what authorities, if any, the administration would need after that date. Schiff’s amendment failed, but it did gain 185 “yes” votes in the House, 155 of them from Democrats.

Even President Obama has expressed at least vocal support for further circumscribing the AUMF. In his May speech at the National Defense University, the president said, “I look forward to engaging Congress and the American people in efforts to refine, and ultimately repeal, the AUMF’s mandate.” Thus far, however, the Obama administration has evinced little to no apparent interest in actually pursuing this course.

The main problem regarding the AUMF right now is well understood: that even as the U.S. government apparently has been largely successful in crippling the original “core” Al Qaeda network in Pakistan and Afghanistan, there has been a concurrent rise of terrorist organizations in other countries whose operational connections to core Al Qaeda are tenuous or unclear. In some cases, most notably Al Qaeda in the Arabian Peninsula, whose links to core Al Qaeda are more robust and which has directly targeted the United States, applying the AUMF is not very controversial. But other cases are far less clear-cut. The Washington Post reported in March that the government was “weighing whether the law can be stretched to cover what one former official called ‘associates of associates.’” These are groups such as Al Nusra Front in Syria that may embrace parts of Al Qaeda’s agenda but have no meaningful connections to its leadership. The result is that there is an enormous deal of confusion over just how far the AUMF reaches.

This confusion was evident in May at a Senate Armed Services Committee hearing in which the Defense Department officials testifying appeared to put forward an extremely broad interpretation of the AUMF. When asked by Senator John McCain if the AUMF could “be read to authorize lethal force against al Qaeda’s associated forces in additional countries where they are now present, such as Somalia, Libya, and Syria,” one witness said, “On the domestic law side, yes.” Another witness answered in the affirmative when asked if, under the AUMF, the president had the authority “to put boots on the ground in the Congo.” As Jack Goldsmith, former head of the Office of Legal Counsel, wrote in recapping the hearing, it was clear that Congress “has no idea how DOD is interpreting the AUMF.” The episode put on display all of the dangers that the AUMF’s critics had warned of—namely, that the law had become the basis for a boundless war with no geographical or temporal limitations, and that it represented an abdication on the part of Congress regarding the legislative branch’s role in issues of war and peace.

What seems clear is that the AUMF is being stretched to its breaking point. As Goldsmith and three other legal scholars—Robert Chesney, Matthew Waxman and Benjamin Wittes—write in a Hoover Institution report, this trend is likely to continue until “even strained interpretations of the AUMF will not be possible.” At that point, the government will be left either holding onto an AUMF that will be seen as increasingly illegitimate, relying on the president’s Article II powers as commander in chief, or ending its targeted-killing campaign entirely (something it is difficult to imagine any administration of either party doing in the immediate future). None of these are appealing options.

Thus, the Hoover report makes the case for a new legal framework to replace the AUMF. It offers a menu of options for what such an authorization might look like. One would be for Congress to specify the “general criteria” that organizations would have to meet in order to be targeted with lethal force. It might, for example, authorize force against “any group or person that has committed a belligerent act against the U.S. or imminently threatens to do so.” The executive branch would then be empowered to identify the organizations that meet this standard. It would regularly report to Congress on what those groups are, the intelligence that forms the basis for listing them and the military actions it is taking to combat the threats.

Another, narrower option that the report describes would be for Congress to do this listing itself, and “authorize the president to use force against specified terrorist groups and/or in specified countries or geographic areas.” The authors warn that Congress might not be able to act quickly enough to meet rapidly evolving threats, and caution that “Congress must under this approach stay engaged politically and legally as threats evolve and emerge; it must debate and approve any significant expansions of the conflict.” But this is precisely what Congress is supposed to be doing. Requiring our legislative branch to reassume the role that it has largely abandoned in the past decade when it comes to matters of war and peace would be a feature of any new authorization, not a bug.

In either of the two above scenarios, Chesney, Goldsmith, Waxman and Wittes recommend that the new AUMF be set to expire after a defined amount of time. In their words, “The authorization should be subject to legislative review and renewal (say, every two years), with a default sunset if Congress does not affirmatively renew the granted authority.” This would be a welcome forcing mechanism to help try to ensure that a replacement AUMF does not simply become the basis for a permanent war that drifts on autopilot, without any congressional debate over whether and to what extent it ought to continue.

One underreported fact in all of this is that the list of organizations that the U.S. government considers itself to be at war with is actually classified. The rationale for this, according to a Pentagon spokesman, is that “because elements that might be considered ‘associated forces’ can build credibility by being listed as such by the United States,” the government “cannot afford to inflate these organizations” by formally listing them. This is the reductio ad absurdum of government secrecy: we can’t tell you who we’re at war with because telling our enemies that we’re at war with them would make them more dangerous. The executive branch could—and should—declassify this list even in the absence of a replacement AUMF. But one of the side benefits of the process of drafting and approving a new one is that it would force this list, along with the debate about who really belongs on it, out into the public eye.

Writing a narrower AUMF that puts real geographical and temporal restrictions on the war on terror, while still preserving the executive branch’s authority to use force against groups that genuinely threaten American security and basic interests, would be a decidedly positive step. As President Obama said in his NDU speech, “In the years to come, not every collection of thugs that labels themselves al Qaeda will pose a credible threat to the United States.” After twelve years of war, it is time for a new legal framework that reflects this reality.