Can Trump deploy the National Guard to US cities? Here’s what the law says

Nevin Al Sukari - Sana'a - With the dome of the US Capitol in the background, members of the DC National Guard keep watch outside Union Station after US President Donald Trump deployed the National Guard and ordered an increased federal law enforcement presence to assist in crime prevention, in Washington, DC, August 19, 2025. — Reuters pic

WASHINGTON, Aug 21 — US President Donald Trump has called upon governors from several Republican states to deploy their states’ National Guard to Washington, DC, which Trump has claimed is ridden with crime. As troops poured into DC, Trump on Tuesday also suggested that he might send the National Guard to other cities.

Here’s a look at the authority Trump has to deploy troops in DC and cities around the U.S.

Does US law permit military policing?

A federal law called the Posse Comitatus Act generally restricts the use of the US military for domestic law enforcement purposes.

This 1878 law embodies a long-held American belief that involving the military in civilian affairs is a threat to personal liberty.

But there are exceptions to the Act, and the law often does not apply to actions by National Guard troops under the command of a state’s governor.

What authority did Trump use to activate the National Guard in DC?

Unlike other states, the National Guard of Washington, DC, a federal district, reports directly to the president and Trump has full authority to activate them.

Trump announced on August 11 that he had ordered 800 Guard troops in response to what he said was high crime, a characterisation that Democratic mayor of Washington Muriel Bowser has disputed.

Since then, governors of a half a dozen Republican-led states, including West Virginia, South Carolina and Ohio, have announced deployments of National Guard troops in Washington at Trump’s request.

Governors often deploy National Guard in their own state to respond to natural disasters like hurricanes and Minnesota deployed its National Guard in 2020 to help restore order in the wake of protests after the murder of George Floyd by police.

National Guard units also can be fully federalised and placed under federal authority and funding.

The Trump administration has used a third approach, known as Title 32 status, to deploy National Guard troops to Washington. Under this hybrid approach, Guard members are serving under state command and control, but their duties are funded and regulated by the federal government.

The Posse Comitatus Act doesn’t apply to this hybrid approach because the troops remain under state control.

Could Trump deploy troops to other states?

When Trump announced his plans to mobilise the National Guard in Washington, he suggested that other liberal-leaning cities like New York City and Chicago could be next.

But Trump has much less power over these cities than he does over the District of Columbia.

Title 10 of the US Code, a federal law that outlines the role of the US Armed Forces, includes a provision allowing the president to deploy National Guard units into federal service to repel an invasion, to suppress a rebellion or to allow the president to execute the law.

Trump cited this provision, known as Section 12406, when he sent National Guard units to California over the objections of Governor Gavin Newsom.

Trump said he was invoking the provision to protect federal immigration agents and to protect federal property, which the administration has said was not a law enforcement function.

In the case of Chicago, which is a so-called sanctuary city, Trump may argue that local laws that bar city officials from cooperating with federal immigration agents prevent the president from executing the law, justifying the military presence.

Trump is almost certain to face legal challenges if he uses Section 12406 to send National Guard troops from Republican-led states into Democratic strongholds.

A handful of states, including Rhode Island and Texas, have laws preventing other states’ National Guard troops from entering without permission. Some Democratic-controlled states are considering similar legislation.

Are there other ways Trump could deploy troops to cities?

Trump could take the far-reaching step of invoking the Insurrection Act, which is an exception to the Posse Comitatus Act.

There are several conditions for invoking the act, including when there is an insurrection, rebellion or “unlawful obstructions.” The Supreme Court has ruled that the president alone can determine if the act’s conditions have been met.

It has been used 30 times in US history, according to New York University’s Brennan Center for Justice, a left-leaning public policy institute.

Trump could be invited by a governor to invoke the act, as former President George H.W. Bush was in 1992 in response to riots in Los Angeles.

Trump could invoke it on his own if there is a breakdown in law and order or it is needed to defend civil rights. It was invoked in the 1950s and 1960s to enforce school desegregation and protect civil rights marches against the objections of state governors.

What happened in Los Angeles?

Trump in June put California’s National Guard under federal control and deployed them along with active duty USMarines in Los Angeles following protests against his immigration crackdown.

The Justice Department argued that the administration had the authority to do this under Section 12406.

Newsom sued, alleging that the administration violated the Posse Comitatus Act because soldiers engaged in law enforcement, including by briefly detaining people.

A non-jury trial in San Francisco just wrapped up. A ruling from US District Court Judge Charles Breyer is expected soon but it would not be binding on other states and would almost certainly be appealed. — Reuters