A CNN legal expert shed insight into a lawsuit filed by California officials against President Donald Trump on Monday over his decision to federalize and deploy the California National Guard to Los Angeles, bypassing Gov. Gavin Newsom’s authority.

Trump ordered the mobilization of thousands of the state's National Guard troops to the city without Newsom's consent or request, even though Newsom is the commander-in-chief of the state’s troops under both state and federal law. The move was in response to escalating protests in Los Angeles against aggressive federal immigration enforcement actions.

Elie Honig, CNN's senior legal analyst, said Monday evening that the lawsuit just dropped, and he flagged three key points in outlining the lawsuit.

"The law that the Trump administration is using to deploy the National Guard says this: It says the president has the power to deploy the National Guard to a state in any of three circumstances," Honig noted. "First of all, if there's an invasion or a danger of invasion — that's not in play here. Second of all, if there's a rebellion or danger of rebellion, Trump did cite that in his order. And then third, a sort of catch-all — if the president is unable, with regular forces, to execute the laws of the United States. Trump cited that as well."

"The catch — and this is what California, in their lawsuit, really seizes on — is there's language at the end that says orders for these purposes, deploying the National Guard, shall be issued through the governors of the state," Honig emphasized.

That's the crux of the state's main legal argument, he said, that the order was not issued through Newsom.

"This was Donald Trump directly to the National Guard," he noted.

Honig predicted the Trump administration will counter by noting that's a "technicality," and that it's really the president's call. He said he expects that argument to also say there's "no way the law intends to say that the governor can essentially override or cancel the president’s order."

Honig said even legal experts don't know what to expect, as the specific statute has only been invoked once in U.S. history in 1970.

"It involved a postal worker strike, where Richard Nixon — Nixon — deputized the National Guard to deliver the mail. So, a very different scenario. That one didn’t even go to the court. So we are really in unknown territory here," he concluded.

Watch the clip below or at this link.