A protester confronts a line of California national guard troops protecting a federal building in downtown Los Angeles, 9 June 2025. Alamy.com/Eric Thayer

President Trump’s aggressive approach to immigration has provoked mass protest and involved the domestic deployment of the US military. The resulting legal confrontation could become the defining constitutional crisis of his second term.

The scenes of forceful arrests of Latinos by militarised police in Southern California have shocked many Americans. Heavily armed, masked men in military fatigues grabbing peaceful civilians at bus stops. Raids at car washes, building supply stores and farms. Street vendors tackled to the ground. An immigrant father of US citizens violently arrested at his landscaping job. During a raid on a farm, workers were injured and one later died as a result.

Beginning in June, enforcement sweeps by the US Immigration and Customs Enforcement (ICE) agency officers, backed up by national guard troops and US marines, have netted more than 2,600 undocumented migrants in California, according to the government. Officials within the administration of US President Donald Trump have said ICE agents are doing their jobs and executing criminal search warrants, while Trump’s border czar Tom Homan described the farm worker’s death as ‘tragic’.

The aggressive enforcement actions, directed by President Trump and his top administration officials, have raised difficult legal and constitutional issues and led to a backlash of protest from affected communities. Federal courts are now weighing whether President Trump has exceeded the scope of his authority by deploying the American military inside the US to enforce domestic laws.

In early June, after a protest following ICE raids in Los Angeles, the president ordered 2,000 California national guard troops to the city to support ICE and protect a federal detention centre. President Trump later authorised Secretary of Defense Pete Hegseth to deploy an additional 2,000 California guard troops and 700 marines, which he did.

Trump claimed on social media that Hegseth and top US law enforcement officials would ‘liberate Los Angeles from the Migrant Invasion, and put an end to these Migrant riots. Order will be restored, the Illegals will be expelled, and Los Angeles will be set free.’

Normally in the US, national guard troops operate under the control of state governors. President Trump claimed authority under Title 10 of the US Code, which provides for activating national guard for federal service, although only through the office of a state’s governor, which is a route Trump didn’t take in this situation.

‘Fear and terror’ reaches the courts

California Governor Gavin Newsom quickly sued President Trump and Secretary Hegseth in US District Court in San Francisco. In doing so he cited ‘fear and terror spreading in communities across California’. Newsom’s 22-page complaint argued the president failed to fulfil the statutory requirements under Title 10 in order to federalise California’s national guard and violated the US Constitution, which reserves to the 50 states control of such units.

US District Judge Charles Breyer ruled President Trump’s ‘actions were illegal’ and violated the Tenth Amendment to the US Constitution preserving state authority. He issued a temporary restraining order and directed Trump to return control of the California national guard to Newsom. Judge Breyer ruled there had been no ‘invasion, rebellion or inability to execute the laws’ in Los Angeles that would justify deployment of the national guard and marines under the statute.

‘It is not the federal government’s place in our constitutional system to take over a state’s police power whenever it is dissatisfied with how vigorously or quickly the state is enforcing its own laws. Quite the contrary, the Founders reserved that power, and others, to the states in the Tenth Amendment,’ Breyer wrote.

Trump administration lawyers quickly appealed Judge Breyer’s ruling, arguing that the president’s decision to deploy the California national guard was not subject to judicial review.

A Ninth Circuit Court of Appeals panel ruled on 19 June that the president’s deployment of the military to Los Angeles was reviewable. But out of deference to the president’s authority over national security, the appeals panel left Trump in control of the troops while Newsom’s objections are litigated in the lower court.

‘We are not going away. We are here to liberate this city from the burdensome and socialist leadership imposed by this governor and this mayor,’ Homeland Security Secretary Kristi Noem told reporters at a media conference in Los Angeles on 12 June. Noem was referencing California Governor Newsom and LA Mayor Karen Bass.

In an incident caught on video and which gained national attention, Senator Alex Padilla of California was physically ejected from Noem’s press conference after he attempted to question her. Padilla was forced to the floor in a hallway outside and handcuffed.

Padilla has repeatedly condemned the ICE raids as a ‘militarisation’ of Los Angeles and described the Trump administration’s targeting of Latinos in California as ‘cruel’ and ‘extreme’.

Meanwhile, President Trump hailed the Ninth Circuit’s ruling on social media as a ‘BIG WIN’ and claimed that ‘all over the United States, if our Cities, and our people, need protection, we are the ones to give it to them should State and Local Police be unable, for whatever reasons, to get the job done.’

Invoking authority

The District Court in San Francisco is now weighing whether Trump’s deployment of the national guard and marines violates the US Posse Comitatus Act 1878, which limits the president’s ability to use the US military to enforce domestic law within the country. The state of California is arguing that, as an empirical matter, the national guard and marines are effectively engaged with ICE in conducting raids and detaining migrants, not simply protecting federal personnel or property.

The Trump administration contends that the president has broad authority to federalise the national guard in situations of rebellion or when state and local authorities can’t maintain order. The administration further argues that judges shouldn’t second guess the president’s judgment.

A group of service secretaries and retired four-star army generals and navy admirals filed an amicus brief in the case suggesting President Trump’s domestic deployment politicised the military and had failed ‘to adhere to exacting legal requirements and long-established guardrails.’ The deployment posed ‘serious risks to both service members and civilians,’ the authors allege.

Federal troops have been deployed to the states only rarely. In 1957, President Dwight D Eisenhower deployed the Army’s 101st Airborne to enforce the Supreme Court’s landmark school desegregation order in Brown v Board of Education. President Lyndon B Johnson federalised the Alabama national guard in 1965 to protect civil rights marchers led by Martin Luther King. President George H W Bush federalised the California guard at Governor Pete Wilson’s request to help quell massive riots in Los Angeles in 1992.

In all three of these instances, the presidents claimed their authority under the Insurrection Act 1807, which allows them to deploy active-duty military to restore order in cases of rebellion. President Trump has not invoked the Insurrection Act, although he has said he’s considering it.

‘The readiness of the administration to quickly invoke any aspect of this authority is frightening, a message about the willingness of a remade federal government to quell demonstrations,’ wrote Erwin Chemerinsky, Dean of the University of California Berkeley School of Law.

Trump officials, meanwhile, are vowing to escalate the ICE raids and are threatening to impose the military deployment model in Los Angeles on other major US cities. President Trump’s budget – approved by Congress in early July – provides $170bn over the next ten years for a major increase in immigration enforcement. Funding must still be appropriated by Congress but would triple ICE’s agency budget and increase detention capacity to more than 100,000 beds. Personnel and operations would be increased to enable the White House’s goal of 3,000 detentions a day. ‘We’re going to come harder and faster, and we’re going to take these criminals down with even more strength than we ever have before,’ Noem said on 12 July at a media conference.

While President Trump and his deputies have repeatedly characterised the arrests and deportations as a crackdown on criminal aliens, most migrants detained by ICE have no criminal background. And most of those that do have only minor offences on their record, such as traffic violations.

Six California state legislators wrote a letter to President Trump on 27 June urging the administration to focus its enforcement actions on actual criminals, not undocumented workers. ‘Immigrants are essential to the fabric of America,’ the legislators wrote. ‘Unfortunately, the recent ICE workplace raids on farms, at construction sites, and in restaurants and hotels, have led to unintended consequences that are harming the communities we represent and the businesses that employ our constituents.’

Nationwide there were nearly 58,000 migrants in ICE detention as of early July, a record high according to publicly available data from ICE and the US Customs and Border Protection agency (CBP). The US has been deporting about 15,000 people a month since President Trump came into office and those numbers are increasing. Meanwhile, attempted crossings at the country’s southwest border with Mexico have dropped dramatically in the past several months, according to CBP data.

A Quinnipiac University poll in early June showed that overall, 54 per cent of Americans opposed President Trump’s approach to immigration. A Gallup survey taken over the same period found a record 79 per cent of Americans believe immigrants benefit the country while only 30 per cent now favour reducing immigration, down sharply from 55 per cent a year earlier. Gallup noted that support for aggressive deportation has declined.

This divide between broad public unease and hardened partisan support raises the stakes for the courts. If President Trump defies judicial limits, the legal confrontation over the rights of states, military authority and executive power could become the defining constitutional crisis of his second term.

William Roberts is a US-based freelance journalist and can be contacted at wroberts3@me.com