California Governor Gavin Newsom and Attorney General Rob Bonta on Wednesday filed a federal lawsuit against former President Donald Trump, challenging what they described as his “broadly imposed” tariffs.

The lawsuit alleges that Trump unlawfully invoked international economic emergency powers to implement these trade measures.

According to US media reports, the case has been filed in the Northern District of California. It argues that Trump’s use of these powers violates the constitutional principle of separation of powers.

“Trump claims the law gives him authority to impose these tariffs — but he’s wrong,” Governor Newsom said at a press conference. “We’re asking the court to strike down these tariffs and halt their enforcement.”

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Newsom emphasised that the tariffs have disproportionately harmed California, the nation’s largest manufacturing state. He added that they have negatively impacted the U.S. economy and contributed to rising costs for consumers.

Attorney General Bonta noted that this is the 14th lawsuit filed against the Trump administration in the past 14 weeks. “The president is using authority he doesn’t have. He is not above the law,” Bonta said.

In response, White House spokesperson Kush Desai criticised the lawsuit, saying, “While California grapples with crime, homelessness, and inflation, Governor Newsom is busy trying to block President Trump’s historic trade policies.”

Desai added, “We will do everything possible to protect American industries and safeguard our workers.”

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The lawsuit could become a landmark case in the ongoing legal and political debate over trade policy, especially as Newsom is considered a potential presidential contender in 2028.