Why Trump Didn’t Have to Ask Congress Before Striking Iran

President Donald Trump had the authority to order attacks on Iran’s nuclear weapons facilities without seeking congressional approval first.

The claim to the contrary by several members of Congress contradicts decades of U.S. practice involving similar military deployments. Although the Constitution reserves to Congress the right to declare war, exercising that power requires the legislature to take positive action.

Some argue that the War Powers Resolution (WPR) prohibits presidents from unilaterally ordering the use of force. Enacted in 1973, the WPR states that the Constitution permits the president to introduce armed forces into hostilities only “pursuant to (1) a declaration of war, (2) specific statutory authorization, or (3) a national emergency created by attack upon the United States, its territories or possessions, or its armed forces.”

Regardless, nearly every administration since has undertaken unilateral military action broader than that described in the statute. The Justice Department under both Democratic and Republican administrations has justified this by asserting that the president has constitutional authority to independently initiate the use of force when doing so would serve “important national interests” and the anticipated “nature, scope, and duration” of the operation does not rise to the “level of a ‘war.’”

The department’s Office of Legal Counsel (OLC) has repeatedly opined that “military operations will likely rise to the level of a war only when characterized by ‘prolonged and substantial military engagements, typically involving exposure of U.S. military personnel to significant risk over a substantial period.’” Nearly identical positions were expressed under the Clinton administration, the Obama administration and the first Trump administration.

Consistent with this approach, the Clinton OLC concluded that a two-week operation in which the United States flew more than 2,300 sorties over Bosnia in 1995 did not require congressional authorization. The Obama OLC concluded similarly about the 2011 U.S. air campaign in Libya, which lasted over a week and involved the use of more than 600 missiles and precision-guided munitions.

In addition, most administrations have insisted that the WPR amounts to an unconstitutional intrusion into the president’s constitutional authority and that, as a result, the president is not legally bound by the resolution’s interpretation of that authority. Though the three of us might not agree with that interpretation, the reality is that many past presidents have endorsed it.

The Iran situation is at least as compelling as other instances in which prior presidents, of both parties, have unilaterally undertaken the use of force. Unlike some other situations in which recent presidents ordered military action, the threat to the United States from a nuclear-armed Iran is direct. The U.S. would be at grave risk of an Iranian nuclear attack on American naval forces in the Persian Gulf or neighboring air bases, especially considering that Iran has for decades attacked U.S. personnel directly and through its proxies.

The important national interests served by the attacks on Iran’s nuclear weapons facilities have been further delineated in explanations by Presidents George W. Bush, Barack Obama, Joe Biden and Trump of their commitment to use force if necessary to prevent Iran from acquiring a nuclear weapon. Over the past 20 years, Congress has never acted to prohibit or restrict military action. To the contrary, on Nov. 1, 2023, the House of Representatives passed a resolution — by an overwhelming bipartisan vote of 354 to 53 — declaring that “it is the policy of the United States … to use all means necessary to prevent Iran from obtaining a nuclear weapon.”

The U.S. national interest in attacking Iran’s nuclear weapons program was more urgent than ever before, as there is strong evidence that Iran was on the brink of acquiring a nuclear weapon. Additionally, the attack was intended to be limited in both scope and duration, focused on destroying Iran’s Fordow, Isfahan and Natanz facilities. And with the possibility of a ceasefire under discussion between Israel and Iran, Operation Midnight Hammer may have proved to be just that. The operation also derives support from international law as an exercise of collective self-defense in defense of Israel.

If Congress wanted to ensure that the U.S. would not proceed with the strike, it could have acted, and it has the legal authority to halt further engagement if it acts now. Yet, in practice, Congress has repeatedly tolerated presidential decisions to employ military force without congressional preapproval and has consistently supported such actions by appropriating funds to facilitate and sustain these military operations. Congress has not declared war since 1942, and it has only issued a handful of authorizations for the use of military force since then.

Meanwhile, federal courts have frequently rejected as inappropriate for judicial review lawsuits filed by members of Congress challenging presidential authority to use military force unilaterally, even in cases involving apparent violations of the WPR. And the Supreme Court has never ruled on a case involving unilateral presidential military action overseas. With courts repeatedly refusing to enforce the WPR, it is increasingly difficult to maintain that the limits set by that statute meaningfully constrain presidential action.

Over the past week, several lawmakers have introduced bills to limit presidential authority to use force against Iran. But unless and until Congress is successful in passing a law to restrict the president, he is justified in invoking authority just as his predecessors did.

Congress can limit his war power, but to do so it must act, not simply complain after the fact.