The Trump administration argued for the oil companies, and several justices asked whether the court can review the unfinished case at all.
Eight justices heard nearly two hours of argument Monday, Oct. 5, on whether Boulder's Colorado-law climate suit against Exxon Mobil and Suncor can go forward or is barred by federal law. Justice Samuel Alito sat out. He owns stock in ConocoPhillips and Phillips 66, though not in Exxon or Suncor.
The pushback. Chief Justice John Roberts and Justices Neil Gorsuch and Amy Coney Barrett, three conservatives, pressed the companies hard. Roberts said he was "not quite sure what makes this situation different from all those other ones, where we've allowed them to proceed in state court." Justice Elena Kagan compared the suit to tobacco and opioid litigation: "This is Chapter 3. So, if this is Chapter 3, were Chapters 1 and 2 also preempted?" (blocked by federal law). Shanmugam answered that it was a "different book."
The companies' side. The Trump administration backed Exxon and Suncor through Principal Deputy Solicitor General Sarah Harris, a top Justice Department lawyer at the court. Justice Brett Kavanaugh urged the companies to rely on Clean Air Act precedent (past rulings on the main federal air-pollution law) instead of a constitutional theory: "We don't have to reinvent the wheel."
The exit door. Justice Ketanji Brown Jackson told Suncor's lawyer the appeal was "sort of premature from the standpoint of this court exercising its jurisdiction."
Where it stands. A 4-4 tie would leave the Colorado Supreme Court's ruling in place, and Boulder's suit would proceed.
Catch up
On Sept. 28, the Court's clerk told lawyers that Justice Samuel Alito would sit out the case, leaving eight justices to decide whether Colorado climate-damage suits against Exxon and Suncor can proceed. On Oct. 3, Alito, 76, said in a CBS interview that he weighed retiring after last term and will reconsider every year.
How earlier climate suits fared in federal courts
- 2011: Supreme Court ruled 8-0 that the Clean Air Act displaced federal nuisance claims seeking emission caps (AEP v. Connecticut)
- 2021: Second Circuit dismissed New York City's suit because it targeted cross-border emissions directly
- Jan. 2025: Supreme Court declined Honolulu's similar case after the Solicitor General called review premature