Sabin Center Files Amicus Brief in Support of EPA’s 2024 Vehicle Emissions Standards – Climate Law Blog

On Friday, December 6, the Sabin Center filed an amicus brief on behalf of the National League of Cities and the U.S. Conference of Mayors in support of the U.S. Environmental Protection Agency (EPA) in Kentucky v. EPA as part of our ongoing amicus efforts to support strong federal climate regulations. The case involves EPA’s 2024 Vehicle Standards that set new air pollutant and greenhouse gas (GHG) emissions standards for  model year 2027 through 2032 Light- and Medium-Duty Vehicles, which have been challenged by states and industry groups. This case could have a major impact on how and when manufacturers and other entities must reduce their fleet’s GHG and other air pollutant emissions. The Sabin Center’s brief underscores the essential role local governments play in addressing the climate crisis, highlighting their frontline position in mitigating and managing climate impacts.

EPA’s 2024 Vehicle Standards

EPA derives its authority and mandate to promulgate rules regulating “mobile sources” like light- and medium-duty vehicles from Section 202 of the Clean Air Act. Section 202 requires EPA to establish standards of performance for new motor vehicles that “cause, or contribute to, air pollution which may reasonably be anticipated to endanger public health or welfare.” In 2007, the Supreme Court held in Massachusetts v. EPA that EPA has the statutory authority to regulate greenhouse gas emissions from new motor vehicles because carbon dioxide (CO2) and other GHGs fall within the Clean Air Act’s capacious definition of “air pollutant.” Subsequently, in 2009, EPA determined that greenhouse gas pollution threatens Americans’ health and welfare by leading to long-lasting changes in our climate that can have a range of negative effects on human health and the environment. Since 2010, EPA has been regulating GHG emissions and other air pollutants from new motor vehicles. 

Pursuant to its Section 202 authority, EPA finalized a rulemaking in April 2024 that establishes “new, more protective emissions standards for criteria pollutants and [GHGs] for light-duty vehicles and Class 2b and 3 (‘medium-duty’) vehicles that will phase-in over model years 2027 through 2032.” The new rules build upon previous standards EPA issued in 2021 and apply to 2023 through 2026 model year vehicles. EPA’s reasoning for the new rules includes the negative impacts of air pollution on health outcomes, the contribution of GHG emissions from motor vehicles to the worsening effects of climate change, and recent technological developments in zero-emission vehicles (ZEVs) that support a conclusion that more stringent emissions standards are “feasible at reasonable cost and would lead to significant improvements in public health and welfare.” 

The emissions standards become increasingly more stringent over time. For example, the standard for the industry-wide average for light-duty vehicles in 2027 is 170 grams per mile (g/mile) of CO2, while in 2032 it is 85 g/mile of CO2. EPA projects the new standards to significantly reduce CO2 emissions and other air pollutants, with one of their models projecting a net 37 percent reduction in CO2 emissions in 2055 compared to a no-action scenario. One of Petitioners’ main claims is that EPA has exceeded its regulatory authority by setting these fleet-wide standards, arguing that they amount to an “electric vehicle mandate.” However, the Vehicle Standards do not mandate the use of a particular vehicle technology. Rather, the standards are technology neutral, meaning that automakers have the flexibility to comply with the standards through different combinations of gas-powered vehicles, plug-in hybrids, and zero-emissions vehicles like electric vehicles, and also have the option to purchase credits. Moreover, the Court of Appeals for the D.C. Circuit has already affirmed EPA’s authority to take a fleet-wide averaging approach to vehicle regulations under section 202 in NRDC v. Thomas (1986).

Amicus Brief on Behalf of National League of Cities and U.S. Conference of Mayors

The Sabin Center’s amicus brief, filed on behalf of the National League of Cities (NLC) and the U.S. Conference of Mayors (USCOM), argues that cities rely on strong federal standards to bolster their own efforts to mitigate GHG emissions and protect from the impacts and costs associated with climate change. We also argue that the Vehicle Standards fall well within EPA’s authority to regulate mobile sources and that they are critical to ensuring that the federal government remains the leader in mobile source regulation in accordance with the Clean Air Act’s framework. In particular, the Vehicle Standards are a boon to the public health of disadvantaged communities situated near major roadways.

The Sabin Center’s brief describes how cities of all sizes and in every region of the country are disproportionately harmed by the increasingly severe impacts of global heating, and that they must also foot the bill for ever-rising costs associated with climate change. From more frequent and severe hurricanes, to intense heat waves and unprecedented droughts, the health and well-being of cities and their residents are threatened by climate impacts that cost cities billions of dollars each year. 

We also explore the ways in which cities of all sizes lead the response to climate change through mitigation measures that reduce GHG emissions from the transportation sector and creative adaptation solutions that protect urban residents from urban heat and future extreme weather events. Hundreds of cities, large and small, have set ambitious GHG reduction goals and crafted climate action plans that set forth actionable, equitable decarbonization pathways for their communities. Local governments’ transportation sector mitigation efforts include electrifying their fleets and installing electric vehicle charging infrastructure, requiring or incentivizing that electric vehicle infrastructure be installed through building codes or local laws, and investing in alternative forms of transportation. In so doing, they rely on strong leadership from EPA to reduce emissions from vehicles themselves. The Clean Air Act’s opening provision recognizes that vehicles contribute to dangerous air pollution and that federal “leadership is essential for the development of cooperative Federal, State, regional, and local programs to prevent and control air pollution.” 42 U.S.C. § 7401. Because section 209(a) of the Clean Air Act broadly preempts states and local governments from adopting vehicle emissions standards that differ from federal standards, cities rely on strong federal regulation to complement their climate adaptation and mitigation efforts. This is all the more true because cities are uniquely harmed by GHG and other pollutant emissions from vehicles–for example, in densely populated, disadvantaged communities abutting highways. Cities endeavoring to protect those and other residents are constrained in their authority to do so. By promulgating the Vehicle Standards, EPA has fulfilled its statutory mandate to set protective standards critical to the wellbeing of cities and their residents.