Background
To understand how vehicle emissions are regulated, it’s important to understand how vehicles are classified. Both the federal government and California classify vehicles according to their gross vehicle weight rating (GVWR) which determines if a vehicle must meet emission standards for light-duty, medium-duty, or heavy-duty vehicles. The federal classifications are as follows:
- Light-duty Vehicles (< 8,500 lbs): Passenger cars, small SUVs, and light trucks.
- Medium-duty Passenger Vehicles (8,500 – 10,000 lbs): Larger SUVs and passenger vans
- Medium-duty Vehicles (10,000 – 26,000 lbs): Commercial vans, delivery trucks, and buses.
- Heavy-duty Vehicles (> 26,000 lbs): Freight trucks, tractor trailers, and trucks with four or more axles.
In California, vehicles with a GVWR less than 8,500 lbs are regulated as light-duty vehicles. Anything exceeding 8,500 lbs GVWR in California is regulated as a heavy-duty vehicle.
The Environmental Protection Agency (EPA) currently regulates vehicle emissions for light-duty vehicles, medium-duty passenger vehicles, and some heavy-duty vehicles under federal Tier 3 standards. Federal Tier 3 standards require new models of cars to meet average vehicle emissions for pollutants like non-methane organic gasses and nitrogen oxides (NOx). Currently, carbon dioxide (CO2) is the primary greenhouse gas (GHG) subject to federal emission limits that decrease in subsequent years. Non-CO2 GHGs such as methane and nitrous oxide follow strict federal emission caps of 0.03 g/mi and 0.01 g/mi respectively.
New California Regulations
On December 18, 2024, the EPA approved a series of waivers under Sec. 209(b)(1) of the Clean Air Act that grant California the unique right to enforce state-level vehicle emission standards that are stricter than federal standards. California’s waivers enabled the state to enforce its Advanced Clean Cars II, Advanced Clean Truck, and Omnibus Low NOx regulations which are described below:
- Advanced Clean Cars II (ACCII): Beginning with 2026 models, 35 percent of newly sold light-duty vehicles will be zero-emission vehicles (ZEVs), scaling to 100 percent of newly sold light-duty vehicles by 2035.
- Advanced Clean Truck (ACT): Requires ZEVs to make up an increasing percentage of sales with different sales goals for medium and heavy-duty vehicles set by their GVWR. Manufacturers are given more time to reach ZEV sales margins under the ACT due to heavy-duty vehicles’ unique challenges with charging infrastructure and limited electric grid capacity.
- Omnibus Low NOx: Requires new heavy-duty vehicles to reduce NOx emissions by 90 percent below federal standards.
Both the ACCII and ACT are commonly known as California’s electric vehicle (EV) mandate.
House Joint Resolutions 87, 88, and 89: Revoking California’s Regulations
In a blow to California’s EV mandate and NOx regulations, House Joint Resolutions (H.J. Res.) 87, 88, and 89 were signed into law by President Trump on June 12, 2025. Each resolution revokes California’s ACCII, ACT, and omnibus low NOx regulations respectively. These resolutions come amid a transition in powers between the Biden administration that granted California its waivers of preemption in 2024 and the Trump administration that sees those waivers as a threat to jobs, consumer choice, and low vehicle prices.
While the newly passed laws only revoke California’s authority to enforce its EV mandate and NOx regulations, the resolutions affect all states across the nation. Sec. 177 of the Clean Air Act allows other states to adopt California’s more stringent emission standards. Massachusetts, for example, was set to adopt California’s ACCII by 2026 alongside four other states, with six more and D.C. ready to implement the ACCII by 2027. If California loses its authority to enforce its EV mandate, states that rely on Sec. 177 of the Clean Air Act to enforce stricter emission standards would be unable to do so and will revert to federal standards. As such, eleven states, including California, have filed a lawsuit against the EPA and President Trump challenging Congress’ authority to revoke Clean Air Act waivers using the CRA.
Arguments in Favor of H.J. Res. 87-89
California’s EV Mandate Sets Unachievable Standards
The Alliance for Automotive Innovation, a lobbying group representing numerous auto manufacturers across the nation, released a statement upon the signing of H.J. Res. 87-89, stating California’s EV mandates “were never achievable and wildly unrealistic.” In 2024, auto manufacturer Toyota expressed similar concerns about meeting California’s ACCII regulation requiring 35 percent of newly sold light-duty vehicles to be ZEVs by 2026. Recent public data from the California Energy Commission shows that in the third quarter of 2025, 29.1 percent of vehicles sold were ZEVs.
EV Mandates Undermine Consumer Choice
Voicing their support for H.J. Res. 87-89 months before the legislation’s passing, the American Petroleum Institute (API), a representative of the oil and natural gas industry, urged Congress to revoke California’s EPA waivers to protect consumer choice. They argue that forcing 100 percent of new vehicle sales to be EV goes against the demand and preference people have for gas-powered cars. In their statement to Congress, the API references a Gallup poll showing the percent of Americans who own or express interest in owning an EV has declined from 59 percent in 2023 to 51 percent in 2025.
EV Mandates Hurt the Economy
Concerned about the economic impact of an EV mandate, the Specialty Equipment Market Association, a coalition of businesses in the auto manufacturer industry, praised the passage of H.J. Res. 87-89, claiming the resolution will protect American jobs and preserve the economic impact of auto manufacturers. Figures from Calmatter reveal that an EV mandate in California would cause a net loss of 39,800 jobs across the state, accounting for jobs lost and added as a result of the mandate. The construction, insurance, and power sector will see an additional 3,600, 1,700, and 5,600 jobs respectively in a transition towards ZEVs that demand more electricity to power vehicles statewide. Auto mechanics would be hit the hardest with as many as 32,000 auto mechanics projected to lose their jobs. Another 20,831 jobs in state and local governments would be lost as a result of decreased gas tax revenues from an EV mandate.
Technological Limitations of an EV Mandate
Maryland was one of many states preparing to adopt California’s ACCII regulations beginning in 2027.
Initially, the state planned to issue financial penalties to manufacturers that did not comply with the ACCII, but Maryland Governor Moore issued an executive order declining “to pursue penalties associated with any ZEV delivery or sales shortfalls” for model year 2027 and 2028 vehicles. Advocates of H.J. Res. 87-89, like the API, see Maryland’s decision to delay financial penalties as an indicator that the technology and infrastructure isn’t there yet to support an EV mandate.
Arguments Against H.J. Res. 87-89
H.J. Res. 87-89 Were Unlawfully Passed
H.J. Res. 87-89 were passed using the Congressional Review Act (CRA) which allows Congress to “consider legislation to overturn rules” with a simple majority vote in the House and Senate. Both the Government Accountability Office and Senate Parliamentarian advised that the CRA cannot be used to rescind California’s waivers. Congress rejected this advice and moved forward in passing H.J. Res. 87-89. California and several more states are suing, claiming that the CRA’s text makes it clear the law applies exclusively to federal rules enacted by federal agencies. The states also argue waivers of preemption under the Clean Air Act are adjudicatory orders under the Administrative Procedure Act and not “rules.” In a letter sent to Congress days before the House voted on H.J. Res. 87-89, the Natural Resources Defense Council (NRDC), a non-profit environmental advocacy group, expresses concern that “improperly applying the CRA would open up a Pandora’s box, creating a precedent for further attempts to apply the CRA to any number of executive actions outside its scope.”
Vehicle Emissions Harm Air Quality and Health
The NRDC, alongside 127 co-signed businesses and organizations, urged Congress to reject H.J. Res. 87-89, highlighting that “cars, SUVs, and trucks are… a significant source of fine particulate pollution, which causes asthma attacks, heart attacks and strokes, and premature births” and many more health complications that are linked to vehicle emissions. Recognizing potential health risks, California became the first state in the nation to require catalytic converters beginning with 1975 model year vehicles to help combat the severe smog challenges Los Angeles was facing in the mid-20th century.
H.J. Res. 87-89 Cede Global Leadership in EV Production
Governor Newsom has critiqued Congress’ decision to revoke his state’s EPA waivers, claiming the American auto industry will fall behind in the global transition towards clean vehicles. In a public statement, Newsom highlighted how China was responsible for 70 percent of global EV manufacturing production in 2025. The most recently available data shows that, in 2023, the United States accounted for 11 percent of EV production globally whereas China accounted for 55 percent.
Recent Developments
In response to H.J. Res. 87-89, the Affordable Clean Cars Coalition formed with the goal of making EVs more affordable, defending state clean vehicle programs, developing new clean air programs, and more. The coalition currently has thirteen sitting member states with California among them.
Amid pending litigation challenging Congress’ decision, Governor Newsom issued Executive Order N-27-25 on June 12, 2025. Newsom has directed the California Air Resources Board (CARB) to explore the creation of a successor to the ACCII regulations “consistent with state and federal law.” His executive order also directs the CARB to create a list of manufacturers still compliant with ACCII, aiming to provide “additional opportunities to prioritize these manufacturers in government vehicle procurement decisions.”