How the 2002 Iraq AUMF Got to Be So Dangerous, Part 2: Interpretation and Implications

This is the second in a two-part series on the history and interpretation of the Authorization for Use of Military Force Against Iraq Resolution of 2002, or 2002 Iraq AUMF. Part one examined how the 2002 Iraq AUMF has been used over its 20-year history. This article analyzes how the executive branch has come to interpret the 2002 Iraq AUMF and what this means for its potential repeal.

By most accounts, when Congress enacted the Authorization for Use of Military Force (AUMF) Against Iraq Resolution of 2002, it was authorizing the George W. Bush administration to go to war with the Saddam Hussein regime in Iraq. But as the first article in this series documented, use of the 2002 Iraq AUMF did not stop there. Over the subsequent two decades, its language authorizing the use of the U.S. armed forces to “defend the national security of the United States against the continuing threat posed by Iraq” was used not just to remove the Hussein regime but also to facilitate the subsequent occupation of Iraq, including the assumption of responsibility for Iraq’s internal and external security. After the occupation ended, it was cited as the legal basis for an array of similar activities in support of the new Iraqi government, most notably its efforts at combatting al-Qaeda-associated terrorist groups. These efforts ended after the U.S. withdrawal in 2011 but were revived in 2014 when the Obama administration once again intervened in Iraq to lead a military campaign against the Islamic State in Iraq and the Levant (ISIL) terrorist group. The Trump administration in turn implemented a broader campaign against Iran-backed militias in Iraq and even against agents of Iran itself. All of this has been framed as falling within the scope of what the executive branch has consistently described as the 2002 Iraq AUMF’s dual purposes: “helping to establish a stable, democratic Iraq and addressing terrorist threats emanating from Iraq.”

This article examines the interpretive framework that has allowed the executive branch to read the 2002 Iraq AUMF so broadly. In recent years, the executive branch has increasingly justified its interpretations of both the 2001 AUMF—which separately authorizes military operations against the perpetrators of the Sept. 11 attacks, and provides the domestic legal basis for most global counterterrorism operations—and the 2002 Iraq AUMF in terms of its own historical practice. Specifically, it has argued that, where Congress is aware that the executive branch has advanced or acted upon a particular interpretation of the AUMFs, any legislation that appropriates funds for or otherwise engages in those activities serves to confirm Congress’s acceptance of the validity of that interpretation. Viewed through this lens, the 2002 Iraq AUMF becomes an exceptionally broad congressional authorization to use military force so long as there is some relation to Iraq. And while there are ample grounds for criticizing this approach, the fact that it has endured across presidential administrations of both political parties and in spite of legal challenges in the courts suggests that it is unlikely to go away any time soon.

Congress must bear this framework and the interpretations it leads to in mind as it debates the possibility of repeal. Concerns that repeal will limit the executive branch’s ability to confront Iranian militias and other actors threatening U.S. diplomatic and military personnel are misplaced, as the president has substantial authority to act in defense of U.S. personnel and facilities even without statutory authorization. Instead, what repeal will limit is future presidents’ ability to go beyond limited military action and engage in another major war in the Middle East without consulting Congress, which the 2002 Iraq AUMF—as currently interpreted by the executive branch—could readily be read to authorize. While the Biden administration seems unlikely to stretch the 2002 Iraq AUMF to this potential upper bound, future presidents might view the issue differently, especially given Iraq’s complex and often challenging relationship with its neighbor Iran. Nor is it clear whether the Biden administration and federal courts are able and willing to do anything to prevent this from happening unless Congress acts first. 

Historical Practice and AUMF Interpretation

The idea that subsequent practice should bear on how one interprets a statute is, in many ways, a strange one. Modern courts often use such practice to interpret other types of legal texts, such as contracts and treaties, but not statutes enacted by Congress. When interpreting statutes, courts instead look first and foremost to the text of the statute and then potentially to legislative history where the meaning of that text is unclear or otherwise not dispositive. Executive branch views are sometimes cited as confirmation of interpretations based on other grounds and may be entitled to interpretive deference in certain contexts. But the focus is otherwise generally on the intent of the Congress that enacted the statute, not the actions of those who implement the statute afterward.

Subsequent practice does, however, play a central role in how the executive branch approaches the president’s authority to use military force in a variety of other contexts. In discussing the scope of the president’s constitutional authority to use military force absent any congressional authorization, for example, recent presidential administrations have routinely maintained that “historical practice is an important indication of constitutional meaning” as it “reflects the two political branches’ practical understanding … of their respective roles and responsibilities with respect to national defense[.]” Over time, persistent practice can in turn put a “historical gloss” on how the Constitution is understood to distribute authority. As discussed further below, the executive branch specifically argues that, in the case of war powers, this gloss confirms that the president has broad authority to use military force absent express authorization from Congress, even though the Constitution gives Congress the authority “[t]o declare War.”

The executive branch has also argued that “Congress [can] authoriz[e] and ratif[y] executive branch action through appropriations measures” and other subsequent legislation adopted after the fact, so long as it has the requisite intent to do so. For example, in a 2000 opinion by the Justice Department’s Office of Legal Counsel (OLC) justifying military intervention in Kosovo, the executive branch asserted that “where the President has requested an appropriation in order to continue military operations, evidence showing that Members of Congress were specifically aware of the purposes of the appropriation request will tend to show that Congress intended to authorize continuing military operations[.]” (In the same opinion, OLC also rejected the validity of a provision of the 1973 War Powers Resolution that prohibited Congress from implicitly authorizing the use of force through appropriations and similar measures, on the grounds that one Congress cannot restrict how a future Congress chooses to exercise its legislative authority.)

The executive branch approaches the AUMFs through a combination of these two lenses. Specifically, it has argued that Congress has functionally ratified executive branch interpretations of the AUMFs by knowingly enacting subsequent legislation that appropriates funds for or authorizes activities premised on those interpretations. Of course, this is just one interpretive tool of many that the executive branch applies to the AUMFs. But as use of the two AUMFs has accumulated over their 20-year history, interpretations rooted in past practice have taken on greater significance—especially for the 2002 Iraq AUMF.

The executive branch has made similar arguments about implicit congressional approval since at least the 1970s, if not earlier. But this approach is perhaps most clearly spelled out in the Obama administration’s December 2016 report on the legal and policy frameworks guiding the executive branch’s use of military force and related activities. That report defended the executive branch’s position that the 2001 AUMF extended to ISIL by noting that “Congress has repeatedly and specifically funded the President’s military operation against ISIL through an unbroken stream of appropriations over multiple years.” It observed that Congress had also enacted other legislation contingent on the application of the 2001 AUMF to ISIL, including authorizations for “lethal and nonlethal assistance to select groups and forces fighting ISIL in Iraq and Syria.” Perhaps most importantly, Congress did so while engaging in “close congressional oversight of the status and scope of U.S. counter-ISIL activities, and with knowledge of the specific measures the President was taking to counter ISIL and the statutory provisions under which he was acting.” Together, the report concluded, these measures “convey Congress’s support for the President’s use of force against ISIL, including his determination that he had and continues to have authority to act under prior congressional authorizations for the use of military force.” 

In an endnote, the report also applied this same interpretive framework to the 2002 Iraq AUMF. Echoing earlier statements by officials in the Bush and Obama administrations, among others discussed in the prior piece in this series, it states:

Although the threat posed by Saddam Hussein’s regime in Iraq was the primary focus of the 2002 AUMF, the statute, in accordance with its express goals, has always been understood to authorize the use of force for the related dual purposes of helping to establish a stable, democratic Iraq and of addressing terrorist threats emanating from Iraq. After Saddam Hussein’s regime fell in 2003, the…