The conservative-dominated supreme court voted by seven to two to back a challenge by oil and gas companies, along with 17 Republican-led states, to a waiver that California has received periodically from the federal government since 1967 that allows it to set tougher standards than national rules limiting pollution from cars. The state has separately stipulated that only zero-emission cars will be able to sold there by 2035.

Although states are typically not allowed to set their own standards aside from the federal Clean Air Act, California has been given unique authority to do so via a waiver that has seen it become a pioneer in pushing for cleaner cars. Other states are allowed to copy California’s stricter standard, too.

But oil and gas companies, as well as Republican politicians, have complained about the waiver, arguing that it caused financial harm. The waiver was removed during Donald Trump’s first term but then reinstated by Joe Biden’s administration.