The lawsuit contends that Trump’s move illegally infringed upon Newsom’s role as commander in chief of the California National Guard.
The White House did not immediately respond to a request for comment on the lawsuit.
The suit comes two days after Trump announced the extraordinary deployment in response to protests against immigration raids in the Los Angeles area that have turned violent at times.
It marked the first time in about 60 years that an American President has made such a decision without a governor’s consent.
During a news conferencetoday, Bonta said the Trump Administration “jumped from 0 to 60, bypassing law enforcement expertise and evaluation”.
“They threw caution to the wind and side-lined strategy in an unnecessary and inflammatory escalation that only further spread unrest,” Bonta said.
Trump has argued that federal intervention is necessary because Democratic leaders in California are not acting urgently enough to quell the protests.
Newsom, who has previously clashed with Trump, has argued that the state can handle the protests on its own and echoed Bonta in contending that the deployment is only inflaming the situation.
Newsom, a potential 2028 presidential candidate, previewed the lawsuit earlier during an MSNBC interview.
“[Trump]’s putting fuel on this fire, ever since he announced he was taking over the National Guard - an illegal act, an immoral act, an unconstitutional act,” Newsom said, adding that his state would “test that theory with a lawsuit tomorrow”.
Newsom has already formally asked the Trump Administration to rescind the deployment.
He did so in a letter to Defence Secretary Pete Hegseth that began to lay out legal arguments for how the deployment was hurting the state.
“There is currently no need for the National Guard to be deployed in Los Angeles, and to do so in this unlawful manner and for such a lengthy period is a serious breach of state sovereignty that seems intentionally designed to inflame the situation, while simultaneously depriving the State from deploying these personnel and resources where they are truly required,” Newsom told Hegseth.
Bonta said that Newsom’s request to Hegseth “was ignored”.
The Pentagon chief has shown no signs of backing down and has threatened the deployment of more troops to Los Angeles.
The US Northern Command said that “approximately 500 Marines” stationed in Southern California are ready to deploy to LA if needed.
All of Newsom’s fellow Democratic governors came to his defence in a joint statement, calling the deployment “an alarming abuse of power”.
“Governors are the Commanders in Chief of their National Guard and the federal Government activating them in their own borders without consulting or working with a state’s governor is ineffective and dangerous,” the governors said.