The legal case concerns the EPA's responsibility to establish and review NAAQS for air pollutants. The Court of Appeals for the District of Columbia Circuit accepted some challenges and rejected others regarding the EPA's revision of the NAAQS for particulate matter and ozone. The Supreme Court found that the EPA cannot consider costs in setting the standards, as the text of the statute does not allow it. The Clean Air Act allows the consideration of costs in implementing air quality standards, but respondents must demonstrate a clear textual commitment of authority to the EPA to challenge the EPA's authority to consider costs in setting NAAQS under § 109(b)(1) of the Clean Air Act. The Court has directed the Court of Appeals to address any other challenges to the National Ambient Air Quality Standards (NAAQS) that have been preserved under the judicial-review provisions of 42 U.S.C. § 7607(d)(9). The Supreme Court has upheld the Court of Appeals' jurisdiction over the issue, rejecting the EPA's claims that its policy was not agency "action," was not "final" action, and is not ripe for review.

Justice Thomas agrees with the majority's decision that §109 is an "intelligible principle" and that the Court of Appeals' remand to the agency is incorrect. However, he raises concerns that there may still be a constitutional issue with §109 that was not addressed by the parties. He notes that the parties did not consider the text of the Constitution when discussing the constitutional issue, and that the "intelligible principle" doctrine may not always prevent cessions of legislative power. Justice Thomas suggests that the court may need to reconsider precedents on cessions of legislative power in the future.

Justice Stevens agrees with the Court's decision that the Court of Appeals made an error in concluding that § 109 was an unconstitutional delegation of legislative power. He believes that agency rulemaking authority is legislative power and it would be better to admit it. The definition of "legislation" includes the formulation of rules for the future, and many agencies exercise legislative power by promulgating legislative rules. The author's interpretation of the Constitution is consistent with normal English usage and the text of the Constitution. The Constitution vests "All legislative Powers" in Congress and the "executive Power" in the President, but does not limit their authority to delegate power to others.

The Clean Air Act does not allow the Environmental Protection Agency to consider economic costs when setting national ambient air quality standards. The Act was intended to be "technology forcing" and to establish what the public interest requires to protect the health of persons, even if it means industries will be asked to do what seems impossible at the present time. The legislative history of the Clean Air Act does not suggest an irrational intent by Congress to force technology. The hope of technology-forcing can be realistic, as demonstrated by the development of catalytic converter technology that helped achieve substantial reductions in auto emission pollutants without the economic catastrophe that some had feared.