Research checked 27 September 2026 · Official docket
The competing views
The central issue is whether the Constitution and federal law, including the Clean Air Act, prevent Colorado law from supplying a remedy for harm linked to emissions across state and national borders. The Court has also asked whether it has legal authority to hear this appeal at this stage. If it cannot hear the appeal, it may leave the central question unanswered.
Suncor and ExxonMobil argue that making producers pay under one state’s law would effectively let that state regulate a global emissions problem. They say the constitutional division of powers and the Clean Air Act rule out these claims.
Boulder says it seeks compensation for local harm caused by the companies’ sales and deceptive marketing, rather than court-ordered emissions limits. It argues that federal air-pollution law does not remove these state-law remedies, and that Supreme Court review is premature.
Original summaries of submissions, not findings of fact.
Procedural history
- 27 April 2018
Underlying lawsuit filed in Colorado state court
- 12 May 2025
Colorado Supreme Court rejects federal preemption defence; claims may proceed
- 23 February 2026
Review granted; jurisdiction question added
- 14 May / 27 July 2026
Merits briefs filed
- 5 October 2026
Argument scheduled; not yet heard as of 26 September
Research & materials
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Case updates
Research and argument schedule checked
The docket records argument scheduled for 5 October 2026. This is a dated research update, not a live feed.
Update source (opens in new tab)Oral argument scheduled
The official docket schedules oral argument for 2026-10-05. Dates may change. Docket entry dated 2026-08-04; checked 2026-09-26.
Update source (opens in new tab)Merits brief filed
The official docket records this procedural event. Docket entry dated 2026-07-27; checked 2026-09-26.
Update source (opens in new tab)