The governor of California, Gavin Newsom, has filed a lawsuit against U.S. President Donald Trump, accusing him of creating economic instability through the imposition of widespread trade tariffs.

The legal action, brought in a federal court in San Francisco, claims that Mr Trump overstepped his authority by introducing tariffs without the required approval from Congress.

Newsom, a prominent Democrat and long-time critic of Mr Trump, said the tariffs have caused significant economic harm to California, the fifth-largest economy in the world if measured independently, as well as to the broader United States.

The lawsuit, co-filed with California’s attorney general Rob Bonta, argues that key trade partners like China, Mexico and Canada have been unfairly targeted, to the detriment of local industries and consumers.

The president has enacted 10% tariffs on all imported goods, with steeper levies for countries he claimed had high barriers to American exports.

While some, like the 25% tariff on EU goods, were paused for 90 days, others – including a massive 145% tariff on Chinese imports – triggered strong retaliation.

China responded with a 125% counter-tariff on US goods.

Mr Newsom, 57, considered a future presidential contender, has previously clashed with Mr Trump over issues such as California’s response to wildfires.

Speaking on the latest legal move, he warned: “No state is poised to lose more than the state of California.”

This case joins two other lawsuits against Mr Trump’s trade policies: one filed in New York by a national business group, and another in Florida by a small business owner.

The Californian suit aims to block customs authorities from enforcing the tariffs until congressional approval is secured.

Photo: California Governor Gavin Newsom. (Photo by Justin Sullivan/Getty Images)