Speaking with reporters on the White House lawn, President Donald Trump played coy when asked if he would bring the United States into Israel’s war on Iran.

“I may do it. I may not,” he said on Wednesday.

Recommended Stories

list of 3 items

end of list

US officials and the president’s allies have stressed that the decision to get involved in the war – or not – lies with Trump, stressing that they trust his instincts.

“He is the singular guiding hand about what will be occurring from this point forward,” Department of State spokeswoman Tammy Bruce told reporters on Tuesday.

But antiwar advocates have been arguing that it should not all be up to Trump and Congress must be the ultimate decider over war and peace, according to the US Constitution.

As Trump increasingly appears to hint at the possibility of US engagement in the conflict, some lawmakers are seeking to reassert that congressional role under the War Powers Act.

But what are the laws guiding a declaration of war, and could Trump get the US involved in the war without the consent of Congress?

Here’s what you need to know about the laws that govern decisions about war in the US.

What does the US Constitution say?

Section 1 of the US Constitution, which established the legislative branch of the government and outlines its duties, says Congress has the power to “declare war”.

Some advocates take that provision to mean that lawmakers, not the president, have the authority over US military interventions.

When was the last time the US formally declared war?

In 1942, during World War II. Since then, the US has gone to war in Korea, Vietnam, the Gulf, Afghanistan and Iraq while carrying out strikes and interventions in numerous countries – Serbia, Libya, Somalia and Yemen to name a few.

Advertisement

What authority does the president have when it comes to war?

According to Article II of the constitution, the president is designated “commander in chief” of the armed forces.

Presidents have the power to order the military to respond to attacks and imminent threats. Beyond that, their war-making powers are constrained by Congress. Article II empowers them to direct military operations once Congress has authorised a war. They are responsible for mobilising the military under the guidelines of lawmakers.

That said, successive presidents have used the ability to direct the military on an emergency basis to carry out attacks that they frame as defensive or in response to threats.

How has the US sent soldiers into Iraq and other places without formal declarations of war?

Short of a declaration of war, Congress may grant the president powers to use the military for specific goals through legislation known as the Authorization for Use of Military Force (AUMF).

For example, in the wake of the 9/11 attacks in 2001, Congress passed an AUMF that gave then-President George W Bush broad powers to conduct what would become the global “war on terror”.

And one year later, it passed another AUMF allowing the use of the military against the government of Saddam Hussein in Iraq, which became the basis of the 2003 invasion.

The two authorisations remain in place, and presidents continue to rely on them to carry out strikes without first seeking congressional approval. For example, the assassination of top Iranian General Qassem Soleimani in 2020 in Baghdad was authorised by Trump under the 2003 AUMF.

During Trump’s first term, there were concerns that he could use the 2001 AUMF to strike Iran under the unfounded claim that Tehran supports al-Qaeda.

When was the War Powers Act passed?

Despite the articles outlined in the constitution, presidents have found ways to sidestep Congress in war matters. So in 1973, after decades of US intervention in Vietnam and elsewhere in Asia, lawmakers passed the War Powers Resolution to reassert their authority over military action.

The law restricts the president’s war-making powers – or that was its intention at least.

It was passed after President Richard Nixon’s secret bombing of Cambodia, which killed tens or even hundreds of thousands of civilians and led to widespread protests in the US.

What are the key provisions of the War Powers Act?

The federal law was designed to limit the US president’s power to commit the US to armed conflict.

Advertisement

Enacted over Nixon’s veto, the resolution requires “in the absence of a declaration of war” that the president notify Congress within 48 hours of military action and limits deployments to 60 or 90 days unless authorisations to extend them are passed.

Before US troops are committed abroad, Congress must be consulted “in every possible instance”, it says.

Why is the War Powers Act relevant now? 

With the possibility of a US intervention in Iran mounting, lawmakers have been eyeing the five-decade law and pushing for their own version.

On Monday, Democratic Senator Tim Kaine introduced a bill requiring that Trump, a Republican, seek authorisation from Congress before ordering military strikes against Iran. That was followed by a similar bill put forward in the House of Representatives on Tuesday by US Representatives Thomas Massie of Kentucky, a Republican, and Democrat Ro Khanna of California.

A No War Against Iran Act, introduced by Democratic Senator Bernie Sanders of Vermont, seeks to “prohibit the use of funds for military force against Iran, and for other purposes”.

But even as some polls find Trump supporters are against war with Iran, passage of such bills in the Republican-controlled legislature remains unlikely.

Why is new legislation needed if it’s in the constitution? 

Despite the constitutional separation of war powers, the executive and legislative branches have jockeyed over those roles throughout US history.

The most prominent of these incidents – and the last time such a case made it to the Supreme Court in fact – took place in 1861 at the start of the US Civil War when President Abraham Lincoln blockaded southern ports months before Congress legally declared war on the Confederacy. The highest court eventually ruled the president’s acts were constitutional because the executive “may repel sudden attacks”.

Throughout history, formal congressional declarations of war have remained scarce. There have been just 11.

Instead, Congress has traditionally authorised a wide range of military resolutions.

Does the War Powers Act have any teeth?

Almost since its passage, the 1973 law has been viewed by some critics as deeply ineffective – more of a political tool for lawmakers to voice dissent than as a real check on power. (In the 1980s, then-Senator Joe Biden led a subcommittee that concluded the law fell short of its intent.)

Congressional resolutions seeking to end military involvements unauthorised by Congress are subject to a presidential veto, which can be overridden only by two-thirds majority votes in the House and the Senate.

Others have argued the law served an important role in asserting Congress’s rights and creating a framework for speedy, presidential reporting to Congress. The more than 100 reports that have been sent to Congress since 1973 offer a semblance of transparency.

How do presidents view the act?

While Nixon was the most vociferous in his opposition to the War Powers Act, he’s hardly the only president to appear critical. Modern presidents have routinely sidestepped the act, using creative legal arguments to work around its requirements.

Advertisement

The executive branch has since steadily expanded its war-making powers, particularly after the September 11, 2001, attacks.

The 2001 AUMF and the 2002 Iraq AUMF have been used to justify attacks on “terrorist groups” in at least 19 countries, according to the Friends Committee on National Legislation.

“The executive branch has stretched this authorization to cover groups that had no connection to the 9/11 attacks, including those such as ISIS [ISIL], which did not even exist at the time,” Heather Brandon-Smith, the nonprofit’s legislative director of foreign policy, wrote in a briefing.

And while organisations like the International Crisis Group have urged a rehaul or repeal of the AUMF, successive administrations have shown little interest in doing so. In recent years, congressional efforts to repeal the 2001 and 2002 AUMFs have only begun chipping away at the acts.

The Senate in 2023 voted to repeal the 2001 AUMF although the move was largely viewed as symbolic. The House similarly voted to repeal the 2002 AUMF in 2021. But both laws still remain in effect.

Can the War Powers Act stop Trump from going to war with Iran?

That remains to be seen, but it does not seem likely.

During Trump’s first term in office, Congress sought to limit presidential war authority for the first time since the Vietnam War.

In 2019, Congress approved a bill to end US support for the Saudi-United Arab Emirates war in Yemen, which Trump quickly vetoed.

A year later, a similar situation played out after Trump ordered the drone strike that killed Soleimani.

In response, both houses of Congress passed legislation seeking to limit a president’s ability to wage war against Iran.

That legislation was vetoed by Trump, and once again, there were not enough Republicans to meet the two-thirds majority necessary in both houses to override the veto.

With the balance of power in Congress since then fully shifting to the Republicans in Trump’s second term, the newest war powers resolutions face an even stiffer battle.