United States: Clean Air / Pollution

The EPA's proposed redefinition of "begin actual construction" under the Clean Air Act's New Source Review program could fundamentally alter preconstruction permitting requirements for major industrial facilities.

On March 12, 2026, a division of the Colorado Court of Appeals issued a significant opinion concerning federal preemption, aviation law, and environmental nuisance. In Town of Superior v. Board of County Commissioners of Jefferson County, 2026 COA 14, the division held that federal law preempts a state court from ordering an airport proprietor to ban certain aircraft operations as a noise abatement measure, even though the proprietor itself retains the authority to impose such restrictions voluntarily.

The patchwork of carbon pricing regimes across the U.S. and globally has become one of the most consequential – and least discussed – variables in AI data center siting decisions.