When President Donald Trump ordered the assault on Iran that he calls “Operation Epic Fury,” it marked a turning point — both as a challenge to global relations and as a legal test of the American president’s ability to launch an American war without congressional approval.
The United States has not formally declared war since World War II. The Constitution gives that power exclusively to Congress.
Yet, from Harry Truman to Barack Obama to Trump, presidents have unilaterally ordered large-scale, impactful military operations with major geopolitical consequences. Major conflicts, including Korea, Vietnam and both Gulf wars, were fought not with formal declarations of war, but under relatively vague congressional acts known as Authorizations for Use of Military Force.
As in past cases, Trump’s decision has drawn sharp criticism from across the globe. Some members of Congress and international law experts, as well as Iran’s prime minister, claim Trump’s order was unconstitutional, particularly because the attack was coordinated with Israel, but without any sign-off from Congress.
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“[W]e’ve launched a full-scale war in the Middle East, and the President has not made his case to the American people,” Rep. Adam Smith, D-Wash., the ranking minority member on the House Armed Services Committee, told NPR. “He’s not made his case to Congress. He’s not asked for congressional support. That’s illegal. … [I]t is also directly contrary to how a constitutional republic is supposed to function.”
Others have rallied behind Trump, supporting his bold attacks on Iran.
“As I watch and monitor this historic operation, I’m in awe of President Trump’s determination to be a man of peace but at the end of the day, evil’s worst nightmare,” Sen. Lindsey Graham, R-S.C., wrote Saturday on X. “Well done, Mr. President.”
Congress is poised for a highly charged debate this week on whether to invoke the War Powers Act of 1973 and shut down Trump’s military action in Iran.
But what is the War Powers Act? And if Trump’s “Epic Fury” was illegal, will there be consequences?
US presidents order de facto wars
Trump is the most recent in a long line of presidents who have tested the boundaries of their executive authority.
President George H.W. Bush sent troops into Panama to arrest that nation’s leader, Manuel Noriega, on U.S. drug charges and then, under an Authorization for Use of Military Force, deployed forces to drive Iraq out of Kuwait in Operation Desert Storm.
Bush’s successor, President Bill Clinton, approved military action in Kosovo and Haiti.
After the terrorist attacks of Sept. 11, 2001, Congress passed another Authorization for Use of Military Force that Presidents George W. Bush and Barack Obama cited repeatedly as backing for military actions — including invasions of Afghanistan and Iraq and relatively limited strikes on Libya and Syria.
In his second term, Trump has ordered military actions without seeking congressional approval, before or after the fact.
Last year, he authorized the military to take lethal action against boats in the Caribbean and the eastern Pacific Ocean that were allegedly carrying drugs toward the U.S.
Then, at the beginning of 2026, Trump sent U.S. troops into Venezuela to capture that country’s president, Nicolás Maduro. Some experts say the action violated international law, as well as the Constitution.
Under Article I, Section 8 of the Constitution, Congress is granted exclusive authority over waging war, under what is known as the Declare War Clause.
“The Declare War Clause is a central element of Congress’s war powers and its meaning is among those most heavily debated,” Constitution Annotated, published by the Congressional Research Service, says. “The Supreme Court has observed that only Congress has the power to declare war, but the implications of this exclusive assignment are not well-settled.”
In 1973, Congress sought to clarify its authority by passing the War Powers Resolution — also known as the War Powers Act. It allows the president to initiate military action, but only if he notifies Congress within 48 hours and intends to pull out forces within 60 days. The resolution was a reaction to President Richard Nixon’s secret order to bomb Cambodia during the Vietnam War.
On Monday, Secretary of State Marco Rubio said the War Powers Act did not apply to the Iran strikes because it would not have been possible to notify every member of Congress before the attacks began.
“We complied with the law 100% and we’re going to continue to comply with it,” Rubio said.
But Adam Smith, the top Democrat on the Armed Services Committee, told NPR that Republican congressional leaders have failed to hold the Trump administration accountable.
“[T]he Republican Congress under Mike Johnson and John Thune have simply abdicated all responsibility as the legislative branch and as an Article 1 part of our Constitution,” Smith said. “And this has been happening now ever since Trump got in the White House. You know, Mike Johnson has decided that Congress will simply do whatever Trump wants without questioning them. And so that is a major, major problem.”
What are the consequences?
The courts could intervene to force Trump to stop waging war in Iran. Historically, though, courts have been reluctant to get involved in political questions regarding war.
For the most part, it’s up to Congress to enforce its own authority.
“Congress can — theoretically, if we have the votes — do a lot of things,” Smith said. “Certainly, we can require the president to stop the war until he gets congressional approval.”
“We could also cut off the money,” he added. “We could pass laws that say no appropriations go forward for the war.”
Any action by Congress seems unlikely.
“The idea that we would take away the ability of our commander in chief, the president, take his authority away right now to finish this job, is a frightening prospect to me,” House Speaker Mike Johnson, R-La., told reporters in the Capitol on Monday.
The consequences for Trump’s decision may fall on the balance of power between the executive and legislative branches.
“This is more of an autocratic, monarchical decision,” Smith said, “where he just sort of decided, ‘I’m going to war,’ and did it without getting that approval or even making the case.”
