On March 12, 2025, EPA Administrator Lee Zeldin announced the agency's intention to reconsider 31 environmental regulations, describing the effort as the "single most impactful day of deregulation in EPA history." While the scope of this initiative spans air, water, and climate regulations, the most consequential actions'legally and practically'center on a handful of cross-cutting programs and sector-specific rules.
Although the EPA's announcement is styled as a deregulatory roadmap, none of the targeted rules are rescinded yet. Each proposed rollback will require full notice-and-comment rulemaking under the Administrative Procedure Act (APA), and legal challenges are inevitable. This GT Alert summarizes seven of the most significant rulemakings to watch and highlights the legal and procedural headwinds the EPA is likely to face.
Cross-Sectoral Rollbacks
Greenhouse Gas Endangerment Finding (2009)
The EPA's plan to reconsider the 2009 Endangerment Finding (the "Finding") threatens to upend the legal basis for regulating greenhouse gas (GHG) emissions under the Clean Air Act (CAA).1The Finding, issued following the Supreme Court's decision in Massachusetts v. EPA, required the EPA to determine whether GHGs "may reasonably be anticipated to endanger public health or welfare," leading to regulation of CO₂ and other GHGs from mobile sources.2 The Finding concluded that six greenhouse gases, individually and in combination, contribute to climate change and pose a danger to public welfare.3 The EPA then applied the Finding more broadly to numerous stationary sources under its various CAA authorities.
Any move to revoke or materially alter this determination will face high procedural and evidentiary hurdles under controlling case law; any reversal must be supported by a well-reasoned explanation and contend with extensive factual records supporting both the original Finding and numerous other EPA rulemakings.4 In other words, it is likely to take EPA a fair amount of time to develop a package supporting a revocation of this finding.
Social Cost of Carbon (SCC)
The SCC, a key metric in regulatory cost-benefit analyses, has long been a focal point of legal and policy debate. The Biden administration set the SCC at $190 per metric ton of CO₂, significantly increasing the estimated benefits of GHG regulation and the costs of carbon-based sources of energy. The EPA now proposes to overhaul or potentially abandon the SCC, which could weaken the justification for existing and future climate-related rules.
This proposed shift, if implemented, could make it more challenging for agencies to justify the benefits of greenhouse gas regulations or mitigation measures required via Environmental Impact Statements (EISs). Plaintiffs may challenge the revision on grounds that it arbitrarily discounts intergenerational or global harm.5 Recent case law, includingMissouri v. Biden, has addressed standing and the sufficiency of reasoning behind SCC-related decisions, suggesting courts are increasingly attentive to agencies' cost-benefit frameworks.6 The SCC's reevaluation also resonates with broader post-Loper Brightdevelopments, requiring agencies to justify economic assumptions without the level of deference previously enjoyed.7
Enforcement Discretion and Termination of Environmental Justice (EJ) Programs
The EPA announced the closure of all "Environmental Justice and Diversity, Equity, and Inclusion arms of the agency" and a new posture on enforcement discretion'declining to prioritize actions not clearly tied to statutory mandates.8 Prior administrations have used enforcement actions to impose requirements via administrative consent orders that exceed regulatory requirements and to focus on enforcement of certain sectors. Although this aspect of EPA's announcement is without much detail, the administration is likely to review and potentially change past enforcement...
