The Senate has overruled the guidance of the parliamentarian, a nonpartisan staffer who interprets the Senate's rules, and voted 51 to 44 to overturn a waiver allowing California to set its own air pollution standards for cars that are stricter than national regulations. The Senate has only overruled its parliamentarian a handful of times in the 90-year history of the role.
The Senate has not yet voted on related resolutions to revoke two more waivers related to heavy-duty trucks. One allows California to mandate zero-emission trucks, and the other permits stricter emissions standards for new diesel trucks.
Congress is using a law called the Congressional Review Act, or CRA, as a mechanism to revoke the federal waivers that allowed California to set these rules. The House previously approved three resolutions to revoke the waivers.
But there are significant questions about whether this use of the CRA is legal; the Government Accountability Office and the Senate parliamentarian, who serve as referees within the federal government, both determined that it is not.
The GAO's opinion is merely advisory. The parliamentarian's guidance is also non-binding, but the Senate has traditionally followed it. While disregarding this advice is not unprecedented, it's extremely rare. Historically, leaders of both parties have feared that if they act unilaterally to change the Senate's norms, the other party will do the same when they're in power. That's exactly what happened in 2013 and 2017, when first Democrats and then Republicans deployed the "nuclear option" to eliminate the filibuster for judicial nominees.
"Today it's all about California emission waivers. But tomorrow, the CRA could now be used to erase any policy from an agency that the Trump administration doesn't like at a simple majority threshold," Senate Minority Leader Chuck Schumer, D-N.Y., said Wednesday evening as he tried unsuccessfully to derail the vote. He argued that the CRA could subsequently be used to repeal any policies the White House — including future administrations — doesn't support, including waivers related to Medicaid or reproductive health care. "Republicans should tread carefully today," he said. "What goes around comes around."
Republicans have embraced a legal argument that the CRA can be used in this case. Speaking Wednesday afternoon, Senate Majority Leader John Thune, R-S.D., said that Republicans were not changing the Senate's broader rules or norms, and suggested other reasons for Democratic opposition. "I think a lot of Democrats support an electric vehicle mandate," he said. "In fact I think they're somewhat frantic at the prospect of losing this 'Green New Deal' policy."
California Attorney General Rob Bonta has said that this use of the CRA is unlawful, and the state is expected to challenge it in court. "For more than 50 years, California has exercised its right under the federal Clean Air Act to pursue solutions that address the persistent air pollution challenges that our state faces," Bonta wrote in a statement to NPR after the earlier House vote. "Reducing emissions is essential to the prosperity, health, and wellbeing of California and its families."
Meanwhile, California Gov. Gavin Newsom framed the vote as a national economic issue, arguing that rolling back the standards risks ceding the global EV market to China, where EVs make up a much higher share of production than in the U.S. "The United States Senate has a choice: cede American car-industry dominance to China and clog the lungs of our children, or follow decades of precedent and uphold the clean air policies that Ronald Reagan and Richard Nixon fought so hard for. Will you side with China or America?" he wrote in a statement.
A unique ability
Because of its long history of regulating vehicle emissions, California has the unique ability to establish rules that are more ambitious than the federal ones. Each rule requires a waiver from the U.S. Environmental Protection Agency, and other states can choose to follow California's stricter standards if they want.
California has used this ability to push the auto industry toward zero-emission vehicles for many years, both to protect human health and to reduce the transportation industry's contributions to climate change.
In the first Trump administration, the EPA withdrew a waiver that allowed California to set vehicle standards. A legal battle ensued. Some carmakers sided with the White House and others with Sacramento in the fight over whether that was legal. But the battle became moot after the Biden administration reinstated the waiver.
Since then, California's mandates have become more aggressive, requiring a rapid acceleration in electric vehicle production, starting with 35% of new sales within the state in model year 2026 and reaching 100% of new sales by 2035.
Critics have called that goal unrealistic, given that currently EVs make up about a quarter of new car sales in California, and about 10% of sales nationally. Supporters say that the rules are flexible enough to make them more achievable than they seem.
Supporters also say that the state's standards are more important, the weaker federal rules get — especially with the Trump administration now poised to roll back federal environmental regulations, including on emissions standards.
In April, more than 100 public health and environmental groups sent a letter to Congress saying that blocking the California standards would mean "more children suffering asthma attacks and missing school, more grandparents dying prematurely, and more death and destruction from extreme weather."
The use of the CRA to revoke the waiver is new; last time, Congress wasn't involved and the executive branch withdrew the waiver on its own. But just like during the first Trump administration, expect this decision to trigger a legal battle, as California, climate advocates and health groups are almost certain to defend the state's rules.
Industry allied against the regulations
President Trump campaigned against "EV mandates" and "gas car bans" that would require gas cars to be replaced with electric ones. And while federal EV rules are not technically mandates, California's more aggressive rules do directly require companies to stop selling new gas vehicles (unless they can also run on electricity, like plug-in hybrids do).
The Trump administration has powerful allies in its fight against these rules. The oil industry has repeatedly sued to challenge California's stricter rules. The agriculture lobby, which favors biofuels over batteries, also opposes the California waiver. A group of more than 100 energy, agriculture and transportation trade groups issued a letter in mid-March urging Congress to disapprove the California waivers, arguing the three California rules would "harm American economic and national security" by increasing reliance on battery supply chains that are dominated by China.
The American Petroleum Institute has argued that electric vehicle mandates reduce consumer choice and raise the up-front costs of vehicles. In legal filings and public comments, the group also emphasizes it would cost the oil industry enormously.
"[An EV] mandate would produce widespread effects on the national economy, such as the reduced need for oil and gas production and gas processing, and changes to petroleum refining and distribution," the group wrote in one set of comments in 2024, describing the changes required to meet California's rules as "extraordinary."
Automakers have also opposed the rule, although the issue is more complicated for the auto industry than for the oil industry. Carmakers would like some regulatory stability, since they need to plan vehicle production years in advance. In the name of stability, some automakers previously volunteered to keep following some California regulations during the first Trump administration, when they were disputed.
On the other hand, many traditional automakers think that California's current rules are unrealistic, particularly for the dozen or so states that have opted in to follow those standards. The Alliance for Automotive Innovation, the major automaker trade group, says it would take a "miracle" to meet the rules, because demand for EVs is not as strong as California had hoped.
The auto industry has been lobbying California, and each of the states following its rules, to slow down, pause or soften their strict EV requirements, with some success. But carmakers have simultaneously been lobbying for the use of the CRA to eliminate the California rule altogether, and knock out all those state requirements at once — precisely what's happening now.
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