On February 28, 2026, the United States launched the largest military operation since the 2003 invasion of Iraq. Joint U.S.-Israeli strikes killed Iran's Supreme Leader, destroyed military infrastructure across the country, and initiated a conflict that has cost more than $12 billion, closed the Strait of Hormuz, and sent global energy prices to record levels.
Congress never authorized any of it.
Not a single vote was taken before the first bomb fell. No declaration of war. No authorization for the use of military force. The president acted under his own claimed authority as Commander in Chief, and when Congress tried three times to invoke the War Powers Resolution to halt the operation, it failed every time.
The question of whether the Iran war is legal is not academic. It is the most consequential constitutional question of the Trump presidency — and the answer depends on two pieces of Cold War and post-9/11 legislation that most Americans have never read.
What Is the AUMF?
The Authorization for Use of Military Force is a joint resolution passed by Congress that gives the president statutory authority to use military force. It is not a declaration of war — the United States has not formally declared war since World War II — but it is the legal mechanism Congress has used since the Korean War to authorize military operations.
Two AUMFs have defined American military policy for more than two decades.
The 2001 AUMF was passed on September 14, 2001 — three days after the 9/11 attacks — by a vote of 420-1 in the House and 98-0 in the Senate. Representative Barbara Lee of California was the sole “no” vote in either chamber. The resolution authorized the president to use “all necessary and appropriate force” against those who “planned, authorized, committed, or aided” the 9/11 attacks, or who harbored such persons.
The text contained no geographic limitation, no time limit, and no named enemy organization. It was written to be elastic — and every president since has stretched it. The Brown University Costs of War project documented that the 2001 AUMF was invoked to justify military operations in at least 22 countries. What began as authorization to pursue al-Qaeda in Afghanistan expanded to cover ISIS in Syria, al-Shabaab in Somalia, and armed groups across Africa, the Middle East, and Central Asia.
The 2002 AUMF authorized the Iraq War based on the stated belief that Saddam Hussein possessed weapons of mass destruction — claims later proven false. It was repealed in the National Defense Authorization Act for Fiscal Year 2026, after the Senate voted 66-30 in 2023 to end it.
What Is the War Powers Resolution?
The War Powers Resolution of 1973 is the law Congress passed to prevent exactly the situation the country now faces: a president waging a major war without legislative approval.
Enacted over President Nixon's veto in the aftermath of the secret bombing of Cambodia, the resolution establishes three requirements:
- The president can only commit forces under a congressional declaration of war, specific statutory authorization, or a national emergency created by an attack on the United States.
- Notification within 48 hours. The president must inform Congress whenever forces are committed to hostilities.
- The 60-day clock. Armed forces cannot remain in hostilities for more than 60 days — plus a 30-day withdrawal period — without congressional authorization.
The problem is enforcement. Every president since Nixon has questioned the resolution's constitutionality. No president has acknowledged the 60-day clock as binding. Congress has never successfully forced a withdrawal under the resolution. The law has requirements but no mechanism to compel compliance when a president ignores them.
The 60-day clock on the Iran war expired on April 29. The president has not requested authorization. Congress has not enforced the deadline. The war continues.
Did Trump Have Authority to Attack Iran?
The Trump administration did not cite either AUMF for the Iran war. It could not: the 2002 AUMF had been repealed, and the 2001 AUMF — however broadly stretched — was never intended to cover a state-on-state war with Iran.
Instead, the administration relied solely on Article II of the Constitution — the president's authority as Commander in Chief. In a report to Congress on March 2, the White House stated the strikes were undertaken to protect U.S. forces in the region, protect the homeland, ensure free maritime commerce through the Strait of Hormuz, and act in collective self-defense of allies including Israel.
The administration deliberately avoided calling it a war. Speaker Mike Johnson stated: “We're not at war right now” — this while the U.S. was conducting the most intensive bombing campaign since Operation Iraqi Freedom. Johnson characterized the operation as “four days into a specific mission and operation in Iran, not a full-scale war.”
Legal scholars were broadly skeptical. Article II gives the president some inherent authority to deploy military force, but that authority is generally limited to emergency circumstances — an attack underway or an imminent threat. Former U.S. military officials told The Intercept the attack was illegal. Chatham House concluded that Trump was “making the use of force the new normal and casting aside international law.”
The Congressional Debate
Congress has voted three times to invoke the War Powers Resolution and halt the Iran conflict. All three votes failed.
Senate
House
Senate
Senator Tim Kaine of Virginia, the leading congressional advocate for war powers, called the conflict “an illegal war” and said Trump “started this war on his own — without a clear rationale, without a well-considered plan, without the support of allies, and without the constitutionally-required authorization from Congress.”
Senator Chris Murphy of Connecticut, after attending a classified briefing on the war, told Al Jazeera: “It confirmed to me that the strategy is totally incoherent. If the president did what the Constitution requires and came to Congress to seek authorization for this war, he wouldn't get it.”
The Pentagon has submitted a request for more than $200 billion in supplemental funding for the war. Defense Secretary Pete Hegseth summarized the ask: “It takes money to kill bad guys.” Republican leaders in Congress have not brought the funding request to a vote, in part because they do not believe they have the votes to pass it even within their own caucus. Representative Lauren Boebert, a Republican from Colorado, stated: “I am a ‘no’ on any war supplementals. I am so tired of spending money elsewhere.”
Historical Precedents
The Iran war is not the first time a president has waged a military campaign without congressional authorization. It is the largest.
The pattern is consistent: presidents act, Congress objects, and the objection fails. Each unauthorized military operation makes the next one easier to justify. The War Powers Resolution was supposed to prevent this escalation. It has instead documented it.
Why It Matters Now
The Iran war has exposed the full extent of the constitutional imbalance between the presidency and Congress on questions of war and peace. The president can launch a major military operation, sustain it for months, spend billions of dollars, and fundamentally reshape global energy markets and international alliances — all without a single affirmative vote from the people's elected representatives.
The constitutional framework is clear: Article I, Section 8 grants Congress the power to declare war. The War Powers Resolution was designed to operationalize that authority. The 2001 AUMF demonstrated what happens when Congress writes a blank check. The Iran war demonstrates what happens when the president does not ask for a check at all.
without congressional authorization,
what is the limiting principle?
Senator Murphy's observation after the classified briefing may be the most important statement anyone in Congress has made about the war: “If the president did what the Constitution requires and came to Congress to seek authorization for this war, he wouldn't get it.”
That is not an argument for the war's illegality alone. It is a description of a constitutional system in which the most consequential decision a government can make — whether to send its military into combat — is made by one person, and the institution designed to check that person has demonstrated that it cannot.
This is a living article. It will be updated as the legal debate evolves. Last updated: April 12, 2026.
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