Ohio v. Environmental Protection Agency

This case involves a challenge by Ohio, Indiana, and West Virginia against the EPA's "Good Neighbor Plan," which aimed to reduce ozone-forming emissions from industrial facilities that drift across state lines. The plaintiff states, joined by industry groups, argued that the EPA overstepped its Clean Air Act authority and that the rule imposed massive compliance costs. The Supreme Court, in a 5-4 decision, stayed the implementation of the plan, finding that the challengers were likely to succeed on the merits because the EPA failed to adequately justify the rule's sweeping requirements. The ruling represents a significant check on federal regulatory power regarding interstate air pollution.

The Supreme Court granted the applications for a stay of the EPA's Good Neighbor Plan in a 5-4 decision, with Justice Gorsuch writing for the majority. The Court held that the challengers were likely to prevail because the EPA's rule failed to reasonably explain its regulatory approach, particularly given that the rule was designed to function uniformly but several critical states had already had their obligations stayed by lower courts. The ruling halted the plan's enforcement nationwide pending further litigation in the D.C. Circuit.

The central dispute focused on whether the EPA acted within its statutory authority under the Clean Air Act's "Good Neighbor" provision by imposing a national emissions reduction plan on states that had already submitted their own compliance proposals. The plaintiffs argued the EPA arbitrarily rejected state plans and enforced a costly federal mandate that was legally flawed, especially since many source states had already been judicially exempted from the rule. The core legal question centered on the likelihood of success on the merits and the irreparable harm caused by compliance costs.

The decision delivered a major blow to the Biden administration's environmental agenda by halting a key air quality regulation aimed at reducing smog. It signaled the Supreme Court's continued skepticism toward broad federal agency actions without explicit congressional authorization, reinforcing the major questions doctrine. Industries praised the reduction of regulatory burdens, while environmental groups warned of adverse public health consequences from continued cross-state pollution. Legally, it created significant barriers for the EPA in implementing collective regional emission control strategies.