Trump’s Unauthorized War
Days after the United States and Israel started bombing Iran, the Trump administration has yet to offer a clear and consistent account of the legal authority behind the strikes. In a brief letter to Congress on Monday, Donald Trump asserts that he “acted pursuant to my constitutional authority as Commander in Chief.” No mention of international law appears in the letter at all. Meanwhile, Democrats in Congress have criticized Trump’s use of force as not just unwise but also unlawful: Speaking on Face the Nation, Senator Chris Murphy of Connecticut condemned what he called “a war of vanity, a war of choice, an illegal war.”
The dynamic between the president and Congress over Iran reflects the problem that has plagued the American political system since Trump’s 2025 inauguration. Trump has pushed and exceeded the limits of executive power. Congress, though weakened, could respond if it wanted to. But under the control of a GOP subservient to the president, the legislature refuses to take up its constitutional responsibilities. Trump’s willingness to single-handedly drag the country into conflict reflects his approach to executive authority more broadly: He takes already extreme conceptions of expansive presidential power and stretches them even further, remaking the presidency into something more like the monarchies reviled by America’s Founders.
A president does not have the constitutional authority to send the country to war on his own. Trump is, as he writes in his letter, the commander in chief of the U.S. military, but the Constitution explicitly grants Congress the power to declare war. That design choice represented a radical break from the monarchies of Europe, where kings and queens had the ability to decide when to mobilize their countries to war.
[Adam Serwer: The American king goes to war]
Yet during the days after Trump’s initial air strikes, Congress has been largely absent. Reporting from Washington, D.C., has instead revolved around the president’s psyche and his erratic theorizing about Iran’s future. Yesterday, Republican senators voted down a measure that would have represented a preliminary step under the War Powers Resolution toward limiting the president’s ability to use force in Iran. The House will proceed with its own vote today, which will also likely fail. In some sense, then, Congress has weighed in—but declining to limit Trump’s use of force is not the same as approving it beforehand. This vote merely underscores that the constitutional system meant to regulate war powers has broken down.
Trump’s disregard for Congress’s prerogative did not come out of nowhere; checks on executive authority have been weakening for decades. Since 1973, when the historian Arthur Schlesinger Jr. published his book The Imperial Presidency, scholars have fretted about the expansion of presidential power over war-making in an unpredictable world. That same year, in response to the catastrophe of the Vietnam War and revelations about Richard Nixon’s secret bombing of Cambodia, Congress passed the War Powers Resolution. The law is meant to constrain presidential uses of force that lack legislative approval. In practice, though, almost everyone agrees that it has been a failure—unable to provide a bulwark against the slow creep of U.S. military deployments and bombings around the globe.
After 9/11, the pace of this constitutional decay accelerated. Under George W. Bush and then Barack Obama, presidents stretched legal arguments to use force abroad in pursuit of the War on Terror—particularly under the Obama administration through a “light footprint” approach that emphasized targeted strikes and one-off raids over sustained deployments. This movement toward presidential unilateralism established both the legal and the political precedents that Trump has drawn on to bomb Iranian nuclear facilities, target boats in the Caribbean, and capture Venezuelan President Nicolás Maduro. “Both Congress and the public have gotten used to presidents using military force without going back to Congress for fresh authorization,” Brian Finucane, a senior adviser at the International Crisis Group, told me.
Each branch of government bears responsibility for this state of affairs. Within the executive branch, the Justice Department’s Office of Legal Counsel has built an edifice of permissive legal reasoning, cobbling together the appearance of authoritative precedent in a process that one group of experts has described as “OLC citing itself citing itself.” Within Congress, lawmakers are often only too happy to avoid responsibility for potentially tough votes on whether and how to use force. The judiciary, meanwhile, has taken itself largely out of the picture, limiting the legal avenues available for challenging the president’s use of force. When Congress passed the War Powers Resolution, it established a means by which the legislature could instruct the president to halt war-making. But the Supreme Court’s 1983 decision in Immigration and Naturalization Service v. Chadha gutted that enforcement mechanism and required that Congress go through the normal legislative process—meaning that any resolution disapproving of executive use of force can simply be vetoed by the president.
Trump’s second-term military adventures have stretched even the permissive limits of these structures. This weekend’s attack on Iran smashes through those limits altogether. “The president has unilaterally kicked off a regional war,” Finucane said. “That is a real departure from prior unilateral uses of military force in recent decades.” In the years since the end of the Cold War, OLC has developed an internal legal test, under which the president may use force without congressional approval if doing so would “serve sufficiently important national interests”—interests, of course, defined by the president—and if the engagement in question would not “rise to the level of war in a constitutional sense.” As my former Lawfare colleague Scott R. Anderson has pointed out, under OLC’s own reasoning, the serious risks of escalation in the Middle East and of American deaths should have weighed heavily against any argument that a conflict with Iran would stay below this level. Already, six U.S. service members have died; yesterday morning, NATO air defenses shot down an Iranian missile headed into Turkey.
[Yair Rosenberg: The real reason Trump went to war]
So far, most GOP members of Congress appear to be sticking with the president. Senator Rand Paul was the only Republican who voted with Senate Democrats to prevent Trump’s attack on Iran without congressional authorization. (Democratic Senator John Fetterman cast his vote against the resolution as well.) In the House, few Republicans are expected to support the companion resolution being voted on today. And even if the GOP had joined with Democrats to pass the measure, Trump would have been able to veto it. Going forward, though, Congress will have other opportunities to rein Trump in, chief among them the ability to restrict funding for a war effort steadily mounting in cost. The congressional power to declare war may have eroded, but the legislature retains the power of the purse—the question is whether it wants to fight for it.
Reserving for Congress the authority to declare war does not mean that Congress will always use its power wisely. The United States has fought its share of legally declared but foolish wars. Still, the requirements of deliberation and debate can press something of a brake on the process of entering into a conflict. Democracy allows people the freedom to make stupid decisions, so long as they make them collectively. But a system that allows a country to be dragged into war at the whims of a single person is not much of a democracy at all.