Trump’s National Guard Deployments Face Legal Hurdles Over 19th-Century Law

WASHINGTON/LOS ANGELES, US President Donald Trump’s decision to deploy the National Guard in American cities is facing a legal challenge over whether it breaches a 150-year-old law restricting military involvement in domestic policing.

Mr Trump on Monday announced a federal takeover of Washington, DC’s police force and the deployment of National Guard troops in the capital, citing a need to curb crime. The move comes as a federal court in California considers whether a similar deployment in Los Angeles last June violated the 1878 Posse Comitatus Act.

The three-day, no-jury trial in San Francisco is examining whether the Trump administration acted unlawfully when it federalised the California National Guard during protests against Immigration and Customs Enforcement (ICE) raids. Despite objections from Governor Gavin Newsom, about 4,000 Guard members and 700 US Marines were sent into Los Angeles to assist in immigration arrests and secure federal property.

California argues the deployment amounted to military involvement in domestic law enforcement – something the Posse Comitatus Act generally forbids unless a rebellion or invasion is underway. Judge Charles Breyer has already ruled the LA protests fell “far short of rebellion” and that the move breached the Constitution’s 10th Amendment on state powers. The Trump administration has appealed, keeping federal control of some 250 Guard members still in California.

The case could set a precedent for future deployments. Legal experts say enforcement of the Posse Comitatus Act is rare, as it requires the US Justice Department to prosecute the executive branch itself.

In Washington, DC, Mr Trump’s order is on firmer legal ground, as the president already commands the city’s National Guard and can assume control of its police force for up to 30 days during an emergency. However, Mayor Muriel Bowser disputes the president’s claim of “total lawlessness,” noting that crime rates are falling after a spike in 2023.

Mr Trump has signalled he may also deploy the Guard to other cities, including Chicago – a plan that could face new obstacles if the California court rules against him.