Molly Nixon
Twenty-five years ago today, terrorists hijacked four commercial airliners and flew three of them into the World Trade Center and the Pentagon, killing thousands of people in the deadliest terrorist attack in American history. The fourth plane crashed after its passengers fought back, preventing the plane from reaching the hijackers’ intended target. On September 15, 2001, Congress gave President George W. Bush an authorization to use military force against those responsible for the September 11 attacks. He signed it on September 18. One week later, the Department of Justice’s Office of Legal Counsel—a small but authoritative division that provides legal advice to the president and the agencies—explained that he had not needed it. The president already held broad constitutional power to use force, OLC concluded, and “Congress’s power to declare war does not constrain the President’s independent and plenary constitutional authority over the use of military force.”
That opinion has never been withdrawn.
Alongside the lives lost and the physical devastation, this is part of what the attacks and America’s response left behind: a more powerful presidency and a written justification for it. The enormous power of the modern executive branch is an overdetermined condition, with trend lines that predate 9/11 by decades, if not centuries. Nearly every president has found the office’s inherent powers more capacious than his predecessor did. But the attacks were met by an administration already primed to advance legal interpretations supporting a strong executive and an influential vice president with long-held views favoring what he called “a robust view of the President’s prerogatives.”
The OLC kept returning to the theme. One opinion derived from “the structure of the Constitution” is the proposition that “any power traditionally understood as pertaining to the executive—which includes the conduct of warfare and the defense of the nation—unless expressly assigned in the Constitution to Congress, is vested in the President.”
Some of these conclusions were controversial inside the Bush administration itself. In February 2005, the OLC advised the Department of Defense that it was withdrawing a 2003 memorandum on the law governing military interrogations of unlawful combatants. Four years later, and five days before Barack Obama took office, OLC went further, withdrawing or cautioning against reliance on several post‑9/11 opinions because, among other things, their propositions “respecting the allocation of authorities between the President and Congress in matters of war and national security” no longer reflected OLC’s views. The September 2001 opinion’s reading of the Declare War Clause was not on the list.
Successful presidential candidates after George W. Bush have run on promises to turn in a different direction. In practice, each has carried the baton further down the track before handing it to an appreciative successor. Nowhere is that clearer than in war powers.
In December 2007, the Boston Globe published Charlie Savage’s executive power questionnaire for the 2008 presidential candidates. Asked when a president may use force without congressional authorization, Obama responded that the president “does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation.” On the campaign trail, he noted the “heavy price” the country had paid for “a president whose priority is expanding his own power” and pledged to “turn the page on the imperial presidency.” The biggest problems America faced, in his view, had “to do with George Bush trying to bring more and more power into the executive branch and not go through Congress at all.”
In office, President Obama soon found merit in his predecessor’s conclusions. When the United States led military operations in Libya in March 2011 to protect civilians during an uprising against the government, Obama’s OLC advised that congressional approval was not necessary because the president “could reasonably determine that such use of force was in the national interest.” The opinion “acknowledged one possible constitutionally based limit on” that presidential authority: “a planned military engagement that constitutes a ‘war’ within the meaning of the Declaration of War Clause,” which would require a fact-specific assessment of the anticipated nature, scope, and duration of the conflict.”
When the operations in Libya went beyond the “limited” strikes described in the president’s representations to Congress and beyond the War Powers Resolution’s 60-day deadline to halt unauthorized hostilities, Obama rejected the views of both OLC and the Pentagon’s general counsel that firing missiles amounted to hostilities subject to that law. And by 2014, whatever he had once thought about presidents who decline to go through Congress, he was vowing not to wait “for legislation in order to make sure that we’re providing Americans the kind of help that they need,” famously observing that “I’ve got a pen, and I’ve got a phone.”
Running in 2016, Donald Trump did not disclaim an expansive view of executive power, but he did reject much of the Bush administration’s post‑9/11 foreign policy, calling for “abandon[ing] the failed policy of nation building and regime change.” Once in office, however, his administration executed air strikes on Syria in 2017 and 2018 in response to chemical weapons attacks on Syrian civilians, apparently relying on inherent Article II powers. Trump’s secretary of state, meanwhile, described a US role in Syria that sounded like themes of both nation-building and regime change.
As a presidential candidate in 2007, Joe Biden had expressed his view that congressional authorization was necessary for any use of force outside an attack or imminent threat. His views on presidential war powers had evolved, however, to largely mirror those of his predecessors. His February 2021 airstrikes on facilities in eastern Syria rested on Article II alone; the report he sent Congress invoked neither the 2001 nor the 2002 AUMF. Beginning in January 2024, Biden reported repeated strikes on Houthi targets taken under Article II power. The Congressional Research Service observed the president’s “apparent claim of Article II authority to protect commercial ships operating under any nation’s flag may represent an expansion of [his] independent Article II authority beyond that which it has asserted in the past.”
Which brings us to the actions taken by the second Trump administration, in some ways the foreseeable products of the early post‑9/11 legal memoranda. In September 2025, the U.S. military began a campaign of boat strikes targeting alleged drug traffickers in the Caribbean and Pacific Ocean. The administration put forward no detailed legal justification (though an OLC memo apparently exists), pointing instead to policy rationales for the strikes. On January 3, 2026, US forces attacked Venezuela and captured President Nicolas Maduro, an operation Trump defended as “rebuilding there and regime change, anything you want to call it,” while asserting that “we’re in charge” in the country.
Eight weeks later, the United States joined Israel in a bombing campaign that killed Iran’s supreme leader. With several shaky pauses, that war has now run for more than six months. Not only is the war unauthorized, but Congress passed a concurrent resolution directing the president to remove US forces from hostilities with Iran.
None of this makes 9/11 the origin of the modern presidency. Presidents have enlarged the office since the founding, most of them without a memo. In December 2005, Vice President Cheney told reporters that the administration had, “to some extent,” “been able to restore the legitimate authority of the presidency,” placing the “nadir of the modern presidency” at the end of the Nixon years and treating what Congress did afterward as an erosion to be undone. Twenty-five years after the attacks, it’s past time for Congress to reclaim its constitutional power; replacing the War Powers Resolution would be a good place to start.
