Whitman v. American Trucking Associations, Inc.

The Clean Air Act directs the EPA (defendant) to set National Ambient Air Quality Standards (NAAQS) that, in the Administrator's judgment, are necessary to protect public health. After the EPA revised the particulate-matter and ozone standards, American Trucking Associations (plaintiffs) challenged them, and the D.C. Circuit held the EPA's interpretation of the statute gave it no intelligible principle to guide its discretion, an unconstitutional delegation of legislative power, and also that costs could not be considered; it remanded to the EPA. The Supreme Court granted certiorari on both issues.

Whether the Clean Air Act's air-quality provision delegates legislative power to the EPA without an intelligible principle to guide it, and whether the EPA may consider implementation costs in setting air-quality standards.