Washington, DC — What began as a regular immigration sweep in several parts of Los Angeles in the US state of California quickly turned to a violent confrontation between immigration authorities and the demonstrators protesting their action.

President Donald Trump immediately deployed thousands of National Guard troops, and later Marines, to Los Angeles, throwing the second-largest  American city into turmoil. 

Since then, US Marines and National Guard have detained people, and Trump has ordered the US Immigration and Customs Enforcement (ICE) to expand immigration raids to Democratic-controlled cities, signalling a potential repetition of the turmoil in Los Angeles.

Conflicting rulings have been issued by a federal court and an appeals court in this case.

Both California's Governor, Gavin Newsom and Los Angeles Mayor Karen Bass have pushed back against the use of the military in LA and accused the president of "illegal militarisation of Los Angeles."

Experts say Newsom and Bass may not be wrong. 

Mark Graber, Regents Professor at the University of Maryland School of Law, told TRT World that the president's deployment of National Guard and Marines to Los Angeles is "probably illegal." 

"The president can deploy only in the case of an invasion or a rebellion, where there is an attempt to overthrow the government and the local government is no longer able to enforce the law," Graber told TRT World.

"Neither is the case in Los Angeles." 

Jacqueline Stevens, a Political Scientist and Deportation Law expert, also said that the action exceeds Trump’s power as president.

“Unlike constitutions that provide extensive ‘emergency’ powers to a national leader, the United States Constitution specifically constrains the powers of the federal government, as enumerated in the Tenth Amendment ‘The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people,’” Stevens told TRT World.

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The Posse Comitatus Act

Generally, a president is allowed to deploy troops to a state in two cases. 

The first case is upon the state's request, where the state's legislature or governor officially requests the deployment from the White House. 

Even Trump himself pointed to this fact in 2020 in an interview with ABC News.

"We can't call in the National Guard unless we're requested by a governor," Trump said at the time.

In the second case, under the Insurrection Act of 1807, the president can deploy troops without the state's request when there is an invasion or rebellion, or when there is unlawful activity that deprives citizens of their constitutional rights and the state is unable or unwilling to protect them.

In his memorandum, Trump didn't invoke the Insurrection Act. Instead, he relied on 10 U.S.C. 12406, a law enacted in 1903 that allows the president to call up the National Guard if there is "a rebellion or danger of a rebellion against the authority of the Government of the United States".

Experts argued that this doesn't apply to the situation in Los Angeles, since the protests don't represent a rebellion or invasion. 

Moreover, there was no request by California to the White House to deploy troops.

By doing so, experts say Trump has violated a law called The Posse Comitatus Act, under which the military can only be used for a domestic purpose when authorised by the law.

Frank Ravitch, a Professor of Law & Walter H. Stowers Chair in Law & Religion at Michigan State University, told TRT World that whether the deployment is constitutional or not, it is "likely illegal."

"The President has relied on a legal provision that allows the use of the military to quell a rebellion, but the protests are not even close to a rebellion, so even if constitutional, the President's actions are illegal as a violation of the Posse Comitatus Act," Ravitch, who is also an author, told TRT World.

"The only other basis to use troops domestically is the Insurrection Act, and the provisions of that have not been met, and the President has not invoked it," he added.

"His best argument would be that the National Guard is only being used to protect federal personnel and property, but even then, the power to do so is limited."

Ravitch said that the last time a President used the National Guard without approval of state officials was in 1965 to protect protesters opposing segregation in the South from violence.

"What Trump is doing is a far cry from that," he said.

Sanford Levinson, who teaches constitutional law and legal history at the University of Texas at Austin School of Law, told TRT World that Trump is acting "like a would-be dictator."

He said while he hopes Trump's actions will be found illegal in courts, the US system gives presidents a "great deal of discretion."

"We often count on Congress to rein in presidents, but the current majority in Congress has adopted an American equivalent of the Führerprinzip, that is, personal loyalty to Donald J. Trump rather than genuine fidelity to the Constitution itself," Levinson told TRT World.

The Fuhrerprinzip, or Leader Principle, was a fundamental element of Nazi Germany, where the leader of the country had absolute authority.

RelatedTRT Global - Los Angeles protests: As second-largest US city sleeps under curfew, families 'scream into fences'

Legal challenges 

With no such case being applicable to the unrest in Los Angeles, Newsom has filed a lawsuit to challenge the military involvement.

In his complaint, Newsom didn't challenge the use of 12406 as a standalone authority, but cited the violation of the Posse Comitatus Act.

"President Trump's Memo purporting to call into federal service members of the California National Guard under 10 U.S.C. 12406 without issuing this order through Governor Newsom is contrary to law and outside of the authority granted to the President under that statute," the complaint said.

"Violation of the Posse Comitatus Act is imminent, if not already underway."

Experts agree with the complaint, saying that the lawsuit could have a legal ground under both the Constitution and the Posse Comitatus Act.

"This can be challenged in courts under both the Constitution and the Posse Comitatus Act," Ravitch said.

"Both protestors, directly impacted, and the state may be able to challenge the military call-up."