Was Donald Trump's decision to bomb Iran unconstitutional?

United States President Donald Trump’s recent airstrikes targeting Iranian nuclear sites have everyone asking one question: can a US president launch offensive military action without direct approval from Congress?

The question has prompted a bipartisan outcry, with lawmakers examining the constitutionality of Trump’s decision and the implications for war powers delegated under US law.

While some have praised the strikes as strategically necessary, others have called them a dangerous breach of executive authority that potentially defies the US Constitution and the War Powers Resolution of 1973.

Did Trump act without congressional green light?

The airstrikes ordered by Trump on June 21 came amid a broader escalation following Israel’s bombardment of Iranian nuclear and military infrastructure.

Though Trump has consistently voiced reluctance to entangle the US in further conflicts in the region, he defended the decision by saying, “Iran can’t have a nuclear weapon.” Yet the timing and unilateral nature of the strikes have raised concerns across both political aisles.

US Defence Secretary Pete Hegseth confirmed during a press conference that Congress was notified only after the aircraft safely exited Iranian airspace. “They were notified after the planes were safely out. But we complied with the notification requirements of the War Powers Act,” Hegseth said.

That admission did little to ease tensions among lawmakers who viewed the operation as constitutionally questionable.

How have lawmakers objected to Trump’s move?

Some of the most vocal objections came from members of Trump’s own party. US Representative Thomas Massie of Kentucky, a Republican known for his strict constitutionalist views, responded to the strikes by stating bluntly, “This is not Constitutional.”

Days earlier, Massie co-authored a resolution with Democratic Representative Ro Khanna of California aimed at preventing unauthorised military action against Iran.

Representative Warren Davidson of Ohio, another Republican typically aligned with Trump, added: “While President Trump’s decision may prove just, it’s hard to conceive a rationale that’s Constitutional.”

Both Davidson and Massie put a spotlight on the requirement for congressional authorisation before initiating military hostilities against a foreign nation.

On the Democratic side, US Senator Tim Kaine of Virginia reiterated his longstanding commitment to reclaiming Congress’s war powers. “We’re going to have the briefing this week. We’ll have a vote,” he said on Fox News Sunday.

“I know many Republicans will fall in line and say a president can do whatever he wants. But I hope members of the Senate and the House will take their Article I responsibilities seriously.” Kaine’s resolution — privileged under Senate rules — can be fast-tracked to the floor and requires only a simple majority to pass.

Other lawmakers have suggested the president’s actions may warrant impeachment.

US Representative Alexandria Ocasio-Cortez of New York posted on social media: “The President’s disastrous decision to bomb Iran without authorisation is a grave violation of the Constitution and Congressional War Powers. He has impulsively risked launching a war that may ensnare us for generations.”

US Representative Sean Casten of Illinois made similar arguments: “No president has the authority to bomb another country that does not pose an imminent threat to the US without the approval of Congress. This is an unambiguous impeachable offense.”

Casten called on Speaker Mike Johnson to protect Congress’s constitutional responsibilities: “Grow a spine.”

US Senator Bernie Sanders, speaking during a campaign event in Tulsa, called the strikes “grossly unconstitutional” and stated, “The only entity that can take this country to war is the US Congress. The president does not have the right.”

House Minority Whip Katherine Clark stated that the power to declare war “resides solely with Congress,” calling Trump’s actions “unauthorised and unconstitutional.”

House Minority Leader Hakeem Jeffries expressed concern that Trump “failed to seek congressional authorisation” and warned that the move could entangle the US in a potentially “disastrous war.”

Despite the criticism, Trump also received support from some lawmakers on both sides of the aisle. US Speaker Mike Johnson said, “The President fully respects the Article I power of Congress, and tonight’s necessary, limited, and targeted strike follows the history and tradition of similar military actions under presidents of both parties.”

Senate Majority Leader John Thune also backed the president’s decision, signalling a likelihood of Republican congressional support.

Some Democrats also refrained from raising legal objections. Representative Steny Hoyer of Maryland and Representative Josh Gottheimer of New Jersey supported the strikes without questioning their constitutionality.

US Senator John Fetterman offered full endorsement of the military action, stating: “Iran is the world’s leading sponsor of terrorism and cannot have nuclear capabilities. I’m grateful for and salute the finest military in the world.”

Are Trump’s strikes on Iran constitutional?

At the centre of the dispute lies the US Constitution. Article I gives Congress the authority to declare war, while Article II names the president as Commander-in-Chief.

The War Powers Resolution of 1973 was introduced to clarify this balance after repeated US military interventions without formal war declarations, most notably in Vietnam and Cambodia.

The War Powers Act mandates that the president notify Congress within 48 hours of deploying US armed forces and limits unauthorised deployments to 60 or 90 days without further congressional approval.

It also requires consultation with Congress “in every possible instance” before initiating hostilities.

Yet the law has often been sidestepped. Presidents have used various justifications — emergency threats, existing authorisations or interpretations of commander-in-chief powers — to engage militarily without a formal declaration of war.

Since World War II, the US has engaged in multiple conflicts — from Korea and Vietnam to Iraq and Afghanistan — without official war declarations.

One major legal instrument enabling military operations without congressional votes is the Authorisation for Use of Military Force (AUMF).

Passed in 2001 and 2002 for operations related to terrorism and Iraq, these authorisations have since been invoked for unrelated operations. For instance, Trump relied on the 2003 AUMF to justify the 2020 killing of Iranian General Qassem Soleimani.

How is this legislation often side-stepped?

In response to Trump’s recent actions, several new legislative measures have been introduced. Kaine’s resolution aims to reassert Congress’s authority before further military engagement with Iran.

Massie and Khanna filed a joint measure in the House based on the War Powers Act to block “unauthorised hostilities.” Sanders introduced the No War Against Iran Act to prohibit federal funds from being used for any military force against Iran.

The ongoing conflict between the legislative and executive branches over war-making powers has been a hallmark of US history.

The US Supreme Court last addressed the issue in 1861 during the Civil War, when it ruled that US President Lincoln’s naval blockade of southern ports was constitutional in the absence of a war declaration because the executive “may repel sudden attacks.”

Still, critics argue that the War Powers Resolution lacks real enforcement mechanisms. Resolutions to end unauthorised hostilities are often subject to presidential vetoes, which require a two-thirds majority in both chambers to override.

While the law provides a framework for transparency and reporting — over 100 such notifications have been sent to Congress since 1973 — it remains a contested tool.

US Representative Ro Khanna said during an appearance on MSNBC: “This is the first true crack in the MAGA base.”

With inputs from agencies