GreenLatinos, et al. v. Suncor Energy (U.S.A.)

Circuit 10Aug 3, 2026

Split Score

SplitScore: 51/100

Case Summary

Disposition

Reversed

Environmental groups sued Suncor under the Clean Air Act’s citizen-suit provision, but the district court dismissed under the diligent-prosecution bar. The Tenth Circuit reversed, holding that only governmental actions presently being litigated in court and enforcing the exact same standards can bar a citizen suit and remanded for further proceedings.

View Full Opinion Document (PDF)

Circuit Split Identified

Legal Issue

Whether the Clean Air Act’s diligent-prosecution bar precludes citizen-suit claims only when the government is already prosecuting the exact same “standard, limitation, or order,” or whether it also bars suits that are merely substantially similar or related.

Circuit Positions

Circuit 9Circuit 10(this circuit)

Diligent-prosecution bar applies only when the government is prosecuting the identical emission standard or limitation alleged in the citizen suit (‘sameness’ requirement).

Circuit 3

Diligent-prosecution bar can also preclude citizen suits over standards that are merely related or substantially similar to those the government is enforcing; a strict textual match is not required.

Conflict Summary

The Tenth and Ninth Circuits read the text strictly, holding that § 7604(b)(1)(B) bars a citizen suit only if the governmental action is enforcing the very same emission standard or limitation pleaded by the citizen plaintiffs. The Third Circuit in GASP v. Shenango rejects that ‘literal, inflexible’ approach and allows the diligent-prosecution bar to preclude suits based on broader, related enforcement activities even when the specific standards differ.

Parties & Counsel

Parties

Appellant:GreenLatinos, 350 Colorado, and Sierra Club
Appellee:Suncor Energy (U.S.A.), Inc.

Legal Counsel

Appellant:Earthjustice (Kirti Datla; Ian Coghill; Rachael Jaffe)
Appellee:Wheeler Trigg O’Donnell LLP (Hugh Q. Gottschalk; Eric L. Robertson) and Williams Weese Pepple & Ferguson PC (Carlos R. Romo; John H. Bernetich)