SACRAMENTO, Calif. — California Gov. Gavin Newsom on Wednesday announced a lawsuit contesting President Donald Trump's executive authority to enact international tariffs without congressional support.

The legal action argues that the International Emergency Economic Powers Act, which Trump cited to impose tariffs, does not grant him the ability to unilaterally adopt tariffs on goods imported into the U.S.

"No state is poised to lose more than the state of California," Newsom said about Trump's tariffs. "That's why we're asserting ourselves on behalf of 40 million Americans."

The case marks the first time Newsom has taken a lead role in any of the now 15 lawsuits that California has filed against the current Trump administration, signaling a deviation from his more reserved approach to the president during Trump's second term. Until now state Atty. Gen. Rob Bonta has acted as the face of California's legal battles against the federal government while Newsom has generally maintained a distance from the back-and-forth court tussles.

Newsom said he chose to take action after absorbing the impacts of the tariffs over the last few weeks. California is the first state to file a lawsuit challenging Trump's tariffs.

"We've been talking to other states, and we're the first mover. That's what California does," he said.

Under the International Emergency Economic Powers Act, Trump has implemented 10% baseline tariffs on all imported goods, higher taxes on goods from Mexico, Canada and China, and specific levies on products and materials such as autos and aluminum. The president threatened and then paused additional tariffs on other nations until this summer.

California, which the governor's office said engaged in nearly $675 billion in two-way trade last year, stands to lose billions in state revenue under Trump's tariff policies if international commerce declines and the stock market tanks. Mexico, Canada and China represent the state's three largest trade partners.

"The gravity and instability of the situation at hand cannot be overstated," Bonta said. "The risk to California, to our businesses, our workers, our families, cannot be overstated."

Bonta said the International Emergency Economic Powers Act does not apply to tariffs.

"The reality is the U.S. Constitution gives Congress the power of the purse," he said. "It's Congress' responsibility to set and collect taxes, duties and excises, including, yes, tariffs, not the president's. Congress hasn't authorized these tariffs, much less authorized imposing tariffs only to increase them, then pause them, then imminently reinstate them on a whim, causing our nation and the global economy whiplash. Trump is attempting to override Congress and steamroll the separation of powers."

Newsom implored Republicans in Congress to do their jobs.

"They're sitting there passively as this guy wrecks the economy of the United States of America, which has dominated the global economy," Newsom said.

Newsom's office said the law specifies the actions the president can take if he declares a national emergency in response to a foreign national security, foreign policy or economic threat.

No president before Trump has used the act to place tariffs on imported products from a specific country or on products imported to the United States in general, according to a description of the law on a congressional website.

The complaint asks the U.S. District Court for the Northern District of California to void Trump's tariff orders, according to Bonta's office.

If California ultimately prevails, requiring Congress to take a vote in Washington to adopt tariffs or allow Trump to enact tariffs could place Republican lawmakers in a vulnerable political position in the midterm elections. A recent poll from CBS News showed that 58% of Americans opposed the U.S. tariffs on imported goods.

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Times staff writer Kevin Rector contributed to this report.

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