Issue: Whether the Environmental Protection Agency (EPA) has the authority under the Clean Air Act to regulate tailpipe emissions of greenhouse gases due to their contribution to climate change and, if so, whether its refusal to exercise this authority is justifiable.
Rule: The Clean Air Act gives the EPA the authority to regulate “any air pollutant” that can “reasonably be anticipated to endanger public health or welfare.” The definition of “welfare” includes impacts on weather and climate.
Application: The Supreme Court analyzed the text of the Clean Air Act and the scientific evidence presented regarding the harm caused by greenhouse gases. It considered the EPA’s reasons for refusing to regulate these emissions.
Conclusion: The Supreme Court held that the EPA has the authority to regulate greenhouse gases as air pollutants and that its rationale for refusing to regulate was insufficient. It directed the EPA to reevaluate whether these emissions cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare.
Detailed IRAC Outline
The detailed issue centers on two key questions:
- Whether the petitioners, led by Massachusetts, have standing to challenge the EPA’s decision not to regulate greenhouse gas emissions from new motor vehicles.
- Whether the EPA’s refusal to regulate such emissions is consistent with its authority under the Clean Air Act.
The legal rules in question derive from:
- The Clean Air Act, which defines “air pollutant” broadly and mandates the EPA to establish standards for the emission of any pollutants that can endanger public health or welfare.
- Administrative law principles that require agencies to act within the scope of their statutory authority and provide reasonable explanations for their actions.
A. Standing of Massachusetts
- Demonstrating Injury: The Court considered whether Massachusetts demonstrated a particularized injury from climate change, such as loss of its coastal land.
- Traceability and Redressability: The Court evaluated whether the injury could be traced to the EPA’s inaction and whether the requested relief would likely redress the injury.
B. Authority of the EPA
- Statutory Interpretation: The Court examined the Clean Air Act’s provisions to determine if greenhouse gases fit within the “air pollutant” definition.
- Mandatory Duty to Regulate: The Court considered whether evidence of harm from greenhouse gases triggered a mandatory duty for the EPA to regulate emissions.
- Scientific Evidence: The Court reviewed the scientific evidence presented regarding the effects of greenhouse gases on climate and public welfare.
C. EPA’s Justification for Non-Regulation
- Scientific Uncertainty: The Court assessed the EPA’s claim of scientific uncertainty as a basis for non-regulation.
- Executive Policy Considerations: The Court evaluated whether considerations of policy, such as potential conflict with the President’s approach to climate change, were legitimate bases for the EPA’s inaction.
The Court concluded that greenhouse gases are air pollutants under the Clean Air Act, and the EPA did have the statutory authority to regulate them. The Court found that Massachusetts had standing due to the potential loss of its territory. The EPA’s reasoning, including scientific uncertainty and policy concerns, was not sufficient to avoid its statutory obligation to regulate if it determined that greenhouse gases endanger public health or welfare. The case was remanded to the EPA to properly consider whether to regulate greenhouse gas emissions from new motor vehicles.