Editor’s note: Please also see the author’s postscript to this article, which discusses the events that have taken place in Iraq and Washington since this issue went to press.

IN JUNE, the jihadist organization now calling itself the Islamic State staged a stunning series of operations to capture large swathes of territory in northern Iraq. In the span of just a few days, the militants seized Mosul and Tikrit and continued marching south. Some observers feared that the Iraqi state itself might collapse completely.

Washington quickly scrambled to try to reverse these gains and bolster the Iraqi government. It sent multiple teams of military advisers to Iraq and positioned more intelligence, surveillance and reconnaissance units in the area. The Department of Defense also announced that it was considering conducting air strikes against the Islamic State in order to break the group’s momentum.

Among those in the U.S. government who must have been scrambling in the aftermath of this advance were the Obama administration’s lawyers. In a strange turn of events, there were in fact three separate legal rationales that could have potentially served as the basis for using military force in Iraq. The first was the president’s power as commander in chief under Article II of the Constitution. The second was the Authorization for Use of Military Force (AUMF) passed in response to the terrorist attacks of September 11, 2001. And the third was the 2002 AUMF that authorized the Iraq War—a war that President Barack Obama had already declared over years before.

At a meeting with congressional leaders in mid-June, Obama reportedly told those present that he did not believe the military options that he was considering required any further congressional authorization. Several senior congressional figures of both parties—including Senate Majority Leader Harry Reid, House Minority Leader Nancy Pelosi and John Thune, the GOP’s third-ranking senator—all suggested publicly that they agreed with this assessment. Jack Goldsmith, a Harvard law professor and former head of the Office of Legal Counsel, likewise argued that same month that “the 2002 Iraq AUMF almost certainly authorizes the president to use force today in Iraq.”

The two AUMFs and the conflicts they underwrote have played an outsized role in the past thirteen years of American foreign policy. Yet both pieces of legislation have also evolved in deeply problematic ways since their passage. One has served as the basis for a conflict surrounded by such a degree of secrecy that many basic facts concerning its scope remain unknown. The other, passed to authorize a war that many Americans would come to think was over, lapsed into disuse and was overlooked by all but a few—but still stayed on the books, with the potential to provide the legal grounds for a future, renewed war in Iraq. Together they tell a story of dangerous drift.

THE 2001 AUMF WAS passed by both houses of Congress with only a single “no” vote between them on September 14, and signed into law by President George W. Bush on September 18. Its central clause gives the president the power 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.

Today, the legislation is understood to authorize force against the Taliban, Al Qaeda and their “associated forces.” It has been used as the legal basis for the war in Afghanistan, the continued detention of prisoners at Guantánamo Bay, and the targeted-killing campaign that the United States has conducted in Pakistan, Yemen and elsewhere.

The Obama administration’s public statements on the scope of the 2001 AUMF have often been vague, but they suggest that its interpretation of the law is quite expansive. At a May 16, 2013, hearing of the Senate Armed Services Committee, Senator John McCain asked Robert Taylor, the acting general counsel of the Department of Defense, whether 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.” Taylor replied, “On the domestic law side, yes.” At the same hearing, Senator Lindsey Graham asked if the president had the authority to “put boots on the ground” in Yemen or the Congo, and Michael Sheehan, the assistant secretary of defense for special operations and low-intensity conflict, answered, “Yes, sir.” Sheehan later attempted to revise this answer, saying, “When I said that he did have the authority to put boots on the ground in Yemen or in the Congo, I was not necessarily referring to that under the AUMF.” But he never stated explicitly that the AUMF would not provide the president with that authority, or clarified what the alternative source of authority would be.

Adding to the confusion is the fact that the administration has refused to tell the public the names of the groups that it considers to be covered under the 2001 AUMF. A Pentagon spokesman explained the rationale for this in July 2013, telling ProPublica that “because elements that might be considered ‘associated forces’ can build credibility by being listed as such by the United States, we have classified the list. We cannot afford to inflate these organizations that rely on violent extremist ideology to strengthen their ranks.” As a result, the U.S. government is in the bizarre situation of considering itself to be at war with a series of organizations while at the same time refusing to tell its own citizens exactly who those enemies are.

The story of the Iraq AUMF is more straightforward. After its passage in October 2002, it served as the legal basis for a disastrous war in which the United States overthrew Saddam Hussein’s regime in early 2003, and then spent nearly nine years attempting to build a new Iraqi state and defend it against insurgents. American military troops completed their withdrawal from Iraq in December 2011. Obama, who had previously touted his early opposition to the war while running for president and campaigned on a promise to end it, declared the war over that same month. However, the Iraq AUMF itself was never actually repealed. And so the 2002 legislation was still in effect when the Islamic State began its march across northern Iraq this summer. As a result, when Washington found itself weighing the use of military force to try to stop this advance, the law was left as an option for the Obama administration to use in order to save it from having to go back to Congress for a new authorization.

THERE HAVE been long-running attempts to repeal or modify both of the AUMFs. In the case of the Iraq War, that effort began in late 2011 as U.S. troops were finishing their drawdown and leaving the country. Then, Senator Rand Paul introduced an amendment to the annual National Defense Authorization Act that would have repealed the Iraq AUMF. The Senate rejected his amendment by a vote of sixty-seven to thirty.

Earlier this year, Paul renewed this effort, introducing a new bill to repeal the law along with Democratic senators Ron Wyden and Kirsten Gillibrand. This time, however, he also had the support of the White House. “The Administration supports the repeal of the Iraq AUMF since it is no longer used for any U.S. Government activities,” said National Security Council spokeswoman Caitlin Hayden. Yet Paul’s bill never received a vote in the Senate. In the House, as the White House was weighing the possibility of conducting air strikes against the Islamic State this June, Representative Barbara Lee (who had previously cast the lone “no” vote against the 2001 AUMF) led a push to ward off this possibility by cutting off all funding in support of the Iraq AUMF—but she too was unsuccessful.

The debate over the 2001 AUMF has been much more sustained. This should not be particularly surprising. Unlike the Iraq AUMF—which, as Hayden said, has not been used as the basis for any military activities since the end of 2011—the 2001 AUMF continues to be used extensively, from Afghanistan to Yemen to Guantánamo Bay. It is thus a natural target for criticism from those who disapprove of many of the actions the United States is taking in the “war on terror.” The New York Times editorial board warned in March 2013 that the authorization was becoming “the basis for a perpetual, ever-expanding war that undermined the traditional constraints on government power.” Accordingly, the board recommended that the law be repealed upon the completion of the withdrawal of U.S. troops from Afghanistan. In the House, Representative Adam Schiff has introduced legislation in each of the last two years that would have done just this. However, both times it has been voted down.

What’s perhaps most interesting is that even many observers who favor waging a continued “war on terror” are unhappy with the current state of the 2001 AUMF. Like the critics, they see that the conflict has evolved significantly over the course of the past thirteen years, and that the enemy that the United States is fighting today is quite different from the one it faced in 2001. The most obvious difference is that while “core” Al Qaeda in Afghanistan and Pakistan has seen its capabilities substantially weakened as a result of America’s military campaign, at the same time numerous other terrorist groups have emerged in other countries. Along with the Islamic State, these include Al Qaeda in the Arabian Peninsula (AQAP), Al Qaeda in the Islamic Maghreb, Al Shabab, Ansar al-Sharia and Al Nusra Front. There are wide variations between all of these groups both in their capabilities and in how connected they are to the original “core” of Al Qaeda. What this means, some say, is that whether or not an organization is an “associated force” of Al Qaeda has ceased to be the best metric in evaluating whether America might need or want to take military action against it. Thus, they argue for rewriting the AUMF to take account of these changes. This might involve specifically listing new groups, or delegating to the executive branch the authority to target certain groups or individuals based on a set of criteria to be determined.

To this point, however, neither group of critics has been successful. At an event earlier this year at the New America Foundation, the Brookings Institution’s Benjamin Wittes explained why. “Everybody hates living under the AUMF,” he said. But, he added, the status quo is also “everybody’s second-worst option.” Human-rights groups worry about the 2001 AUMF being made more permanent, Wittes said, while hawks worry about it being repealed or limited. The White House has expressed a vocal commitment to narrowing and ultimately repealing the AUMF, as Obama outlined in a May 2013 speech at the National Defense University. At the same time, the administration is currently using the AUMF for a whole host of military activities that it perceives as necessary in order to protect American security. The result is an uneasy standoff where almost everybody sees significant flaws in the status quo but simultaneously worries about it being made even worse.

TODAY, BOTH AUMFs remain intact. Both have survived multiple challenges and seem unlikely to be repealed anytime soon. The Obama administration has announced that its “combat mission” in Afghanistan will come to a close by the end of this year. It will leave roughly ten thousand troops in Afghanistan in 2015 and about half that in 2016. However, it has also strongly suggested that the “armed conflict” against the Taliban and Al Qaeda under the 2001 AUMF will not end with this withdrawal. The Department of Defense’s general counsel, Stephen Preston, told the House Armed Services Committee this June that he was “not aware of any determination as yet, that with the cessation of the current combat mission at the end of this year that the armed conflicts are determined to be over.”

But even if nothing is likely to change in the immediate future, it’s worth asking: What should we want to see happen? What would be the ideal outcome to work toward, if the current political obstacles can be overcome?

For the 2002 Iraq AUMF, the answer is clear: it should be repealed. It should have been repealed in December 2011 when U.S. troops finished their withdrawal. It’s not a healthy practice for the government to end its involvement in a war but leave the legal authorization for that war in place. The United States may decide that it is wise to use military force in Iraq again at a level that requires an AUMF from Congress. But the order to use military force then shouldn’t be based on a decade-old legal authorization for a fundamentally different war. The decision should be made by the current Congress based on the merits of the case at the time. Washington may not have conducted air strikes in Iraq this June—but the argument that it could use the 2002 AUMF to do so was apparently persuasive to some legal experts and various members of Congress. Since this law has no temporal limitation, it’s entirely possible that a similar series of events could recur, making it an attractive option for a future president to use to bypass the existing Congress. An outright repeal would eliminate this possibility.

Repealing the 2002 AUMF wouldn’t guarantee that the United States would never employ force in Iraq in the future without congressional approval. President Obama (or one of his successors) might choose to act under his Article II powers as commander in chief—and depending on the circumstances, he might be justified in doing so. When it comes to the Iraq AUMF, however, the bottom line is simple: Either the legislation will be used again or it will not. If it is not, it is therefore superfluous and repealing it would have no consequences. But if it is, this would represent a damaging outcome that ought to be prevented.

Likewise, Congress should also revisit the 2001 AUMF—but first, and just as importantly, the executive branch should answer some very basic questions about it. The administration’s secrecy regarding some elemental facts about this war has made it much more difficult to have an informed public debate on how we ought to proceed. Here are the two most prominent examples:

First, there is very little clarity on the question of which of the actions that the United States has been taking in the “war on terror” require an AUMF in order to be done legally, and which could continue without an AUMF on the basis of the president’s Article II powers. At a hearing of the Senate Foreign Relations Committee on May 21, 2014, Senator Tim Kaine raised precisely this issue. He asked the executive-branch witnesses what the effect of repealing the 2001 AUMF would be on America’s ability to do three specific things: to hold prisoners at Guantánamo Bay; to keep military troops in Afghanistan beyond 2014; and to use the Department of Defense to conduct counterterrorist operations against Al Qaeda. The witnesses did not give clear answers to any of these questions. Rather, they suggested that all of these practices could potentially be affected by the absence of an AUMF, but did not say for sure that any of them would be or to what extent. The administration ought to clarify its interpretation of what it would be allowed to do under Article II. Without this knowledge, it is impossible for Congress or the public to assess with any degree of accuracy what the actual impact of any legislative modifications to the AUMF would be.

Second, the administration should abandon its secrecy on the question of whom we are at war with and publicly name the organizations that it considers to be covered under the 2001 AUMF as “associated forces.” Its official rationale for why it must keep this list classified—that such groups would be made more dangerous if it listed them publicly—is completely unpersuasive. For one thing, the administration has already stated that AQAP is among the organizations on the list, which suggests that it was not worried that acknowledging this fact would “inflate” AQAP’s standing and make the group more threatening to the United States. Furthermore, as Jack Goldsmith has pointed out, the government’s argument ignores the cost of keeping the list classified—namely, the damage it does to the U.S. system of democratic accountability. In Goldsmith’s words, it ignores the public’s interest “in knowing against whom, and where, U.S. military forces are engaged in war in its name”—knowledge which “is minimally necessary for the American people to assess the quality, prudence, and necessity of our military efforts.”

Greater clarity from the administration, particularly concerning its interpretation of Article II, would make it easier for Congress to decide what path to take on the AUMF. But Congress should revisit the AUMF even if this information is not forthcoming. In doing so, it should keep in mind the fact that in 2001, Congress initially conceived of the AUMF as a relatively narrow grant of power. Indeed, it specifically did not adopt the proposed language of the George W. Bush administration, which would have given the president the authority to “deter and preempt any future acts of terrorism or aggression against the United States.” This was the right choice then, and it’s the right way for Congress to think about the law now. The AUMF shouldn’t be seen as a blanket authorization to combat all terrorist organizations and individuals, anywhere in the world they might be.

If Congress revises the 2001 AUMF, therefore, it ought to name the groups that the United States is fighting. It should move away from the existing AUMF’s reference to the events of September 11 and instead focus on those groups that it believes to represent the greatest danger today. The most important criterion for determining which organizations qualify should be whether they are believed to have the capability and intention to launch attacks against the American homeland or, to a lesser degree, U.S. diplomatic and military assets abroad. Based on the intelligence community’s public statements, AQAP would be the most obvious candidate for such an authorization right now. Congress might also wish to include others, depending on whether or not the intelligence supports such an assessment. But this approach decidedly should not encompass terrorist groups whose ambitions are primarily localized. And if and when we reach the point in the future where no organizations meet this standard, then it will be time for the 2001 AUMF to be retired as well.

SOME MIGHT be tempted to ask: How much does all of this matter? Won’t the executive branch still do whatever it sees as necessary in order to combat terrorism independent of what the law says, and then come up with some legal justification to support it? Speaking at the New America Foundation, the Council on Foreign Relations’ Micah Zenko made a version of this argument when he said:

The words that the president—any president—point to to justify using military force don’t constrain him or her. And if the [2001] AUMF is rewritten or not rewritten, it will not make much operational difference in when any president decides to use military force or not. The capabilities exist in great abundance. These are broadly endorsed and supported by the American people. Over 70 percent of Americans in every poll support all sorts of drone strikes no matter how you define the scope of targeting. Appetite in Congress for changing this is next to nothing; oversight of a lot of these sorts of operations is quite minimal. Every president wants maximum authority and minimum oversight, as does this one, as will all future ones. . . . On the current track, there is a path dependency to this perpetual war.

There’s a lot of truth to this. Zenko nonetheless supports the repeal of the 2001 AUMF, writing elsewhere that it “must be pursued as it at least brings a rhetorical end to the post-9/11 counterterrorism framework.” But he correctly warns that the impact of its repeal is likely to be limited. The factors that have led the United States to conduct the “war on terror” in the way it has—among them technological changes and sustained public support—will not disappear even if the AUMF does.

Still, there are at least two additional reasons why increased congressional attention to both AUMFs would be a positive development. First, it would be a good thing from a rule-of-law perspective. No matter what your personal opinion is on the current conflict we are waging, you shouldn’t want to see the executive branch pushing ever more strained interpretations of the law in order to make what it’s doing cohere with words written over a decade ago. And you shouldn’t want to see the U.S. government fall into the habit of declaring wars over but keeping their legal authorizing documents on the books, with the potential to be used by a future president for an unknown future conflict. Even if Congress just replaced the 2001 AUMF with one that more clearly authorized everything the executive branch is currently doing, this would be a positive step simply because it’s a healthier procedure for a constitutional democracy to follow.

Second, a robust debate over both AUMFs would work to create political constraints for the president in addition to legal ones. As many others have observed, the most significant barriers to a president’s ability to wage war are political rather than legal. Recall what happened last year when Obama proposed conducting military strikes against Bashar al-Assad’s regime in Syria following Assad’s use of chemical weapons. Obama said in a speech that he believed he possessed “the authority to carry out this military action without specific congressional authorization.” Nevertheless, he stressed, he was also “the President of the world’s oldest constitutional democracy,” and as such he decided to seek the approval of Congress. This decision was surely not inspired by a philosophical stance, but rather by the political constraints under which Obama was operating. These circumstances included the British House of Commons’ rejection of war and the fact that the prospect of intervention appeared to be quite unpopular with the American public. Thus, Obama decided to take the decision to Congress in order to ensure that another branch of government would be politically accountable for the result that ensued. When Congress appeared poised to reject Obama’s request, he seized upon a diplomatic plan proffered by Russia to provide for the removal of Assad’s chemical weapons.

This was an example of a president acting under real political constraints. In contrast, when it comes to the 2001 and Iraq AUMFs, the executive branch has generally been able to operate without constraints. Congress has made this easier by leaving the Iraq AUMF in place and by remaining largely indifferent to the administration’s broad, vague claims about what the 2001 AUMF allows it to do. It is a textbook example of what former senator Jim Webb called the legislative branch’s “abdication” of its role in defense and foreign-policy matters in a cover story in The National Interest last year. The trend that Webb identified is decades in the making. It is not going to be reversed overnight. But a serious reckoning by Congress with what has happened to the legislation it passed would be as good a place as any to start.

Robert Golan-Vilella is associate managing editor of The National Interest.