California's treasurer and state controller joined officials from nine other states in sending a letter to President Donald Trump Thursday urging him to adhere to the U.S. Supreme Court's ruling on tariffs.

The high court by a 6-3 vote on Feb. 20 struck down the sweeping tariffs Trump had imposed in 2025 in a series of executive orders that caused massive swings in the stock market. The ruling conversely should "be accretive to growth expectations and somewhat disinflationary," Jeff Lipton, The Bond Buyer's market intelligence analyst said in a column the day of the ruling.

California Treasurer Fiona Ma and State Controller Malia Cohen were signatories along with 13 other state financial officers on the letter that asked Trump to adhere to the ruling, ensure that any structural tariff action proceeds only with clear congressional authorization and remedy the economic damage resulting from tariffs inconsistent with the court's guidance.

The majority opinion found the tariffs exceed the powers given to the president by Congress under a 1977 law providing the chief of state with the authority to regulate commerce only during national emergencies created by foreign threats. The constitution vests the power to levy taxes and duties with Congress.

"President Trump's trade policies have injected uncertainty into economies that undermine responsible state budgeting and long-term investment, and it raises real costs for manufacturers and consumers while disrupting supply chains," Ma said. "That's why we must follow the court's decision and restore order — so states can plan responsibly, markets can function with predictability and businesses and families aren't forced to shoulder the cost of policy whiplash."

The 15% global tariff Trump threatened after the ruling was handed down would represent a structural change to the American tax base, the letter states, asserting such a decision belongs to Congress.

"As the state's chief fiscal officer, I believe durable economic growth depends on stability, predictability and respect for constitutional boundaries," Cohen said. "We must restore clarity to protect taxpayers, safeguard state revenues and ensure accountability so that those who have borne these costs will be made whole."

Officials from Washington, Oregon, Minnesota, Colorado, Nevada, Illinois, Maryland, Vermont and Connecticut also signed the letter.

"As we have previously emphasized in public statements, durable economic growth depends on predictability," the letter says. "Trade policy must be stable and clearly grounded in law if markets, employers and state governments are to plan effectively."

California Attorney General Rob Bonta and officials from other states had argued in lawsuits that it was unlawful for Trump to impose tariffs without the consent of Congress.

"While this is great news," Bonta said when the ruling was handed down, "we must not forget the chaos that sent businesses, consumers and global economies reeling. At a time when more and more families are struggling with affordability and having trouble paying for the basics — their utilities, groceries, gas — the administration seems intent on making it more expensive for Californians and Americans to live."

The letter also asked Trump to establish a clear and timely mechanism to reimburse American taxpayers, businesses and affected industries for tariffs imposed without proper constitutional ground, including restitution for demonstrable financial losses borne by the states.

The minority opinion by Justice Brett Kavanaugh raised questions as to whether the federal government will have to provide refunds to importers, which he estimated could cost more than $200 billion.

More than 900 companies have sued the U.S. over Trump's tariffs in the U.S. Court of International Trade, seeking refunds for duties slapped on countries worldwide that they were forced to absorb, the Financial Times reported.