A COURT hearing began today into whether US President Donald Trump violated federal law by deploying the National Guard and marines to Los Angeles in June.

The state of California is asking Judge Charles Breyer to order the Trump administration to return control of the remaining troops to the state and to stop the federal government from using the military in California “to execute or assist in the execution of federal law or any civilian law enforcement functions by any federal agent or officer.”

The hearing, expected to last three days, could have significant implications for future attempts by Mr Trump to deploy soldiers to US cities to impose his will on city and state governments.

All eyes are on it, as the president said at the weekend that he would seek to assert federal control over the capital, Washington DC, claiming that crime was at “ridiculous” levels and vowing to expel all the city’s homeless people. “The homeless have to move out IMMEDIATELY,” he declared on social media.

Mr Trump has so far ramped up the number of Secret Service, Federal Bureau of Investigation (FBI) and US marshals in the city, but he has also hinted at deploying the National Guard, alarming Washington Mayor Muriel Bowser.

California’s case rests on the 1878 Posse Comitatus Act, which prevents the US president from using the military as a domestic police force.

The White House “federalised” (took under federal command) California National Guard members under laws allowing the president to do so when “there is a rebellion or danger of a rebellion against the authority of the government” or when the president is “unable to execute the laws of the United States.”

Huge protests had erupted in Los Angeles against immigration raids and fast-tracked deportations by Immigrations and Customs Enforcement (Ice) officers, but Mr Breyer has already found that the protests fell “far short of ‘rebellion’,” when dismissing a US government bid to have the case cancelled.

After their deployment, the soldiers joined immigration raids in Los Angeles and at two cannabis farm sites in Ventura County, while the marines mostly stood guard around a federal building in Los Angeles that included a detention centre at the core of protests.