Supreme Court Justice Samuel Alito abruptly recused himself Monday from one of the most closely watched cases of the new term, a reversal that comes after months of pressure over his personal stock holdings in oil and gas companies.

The case, Suncor Energy v. County Commissioners of Boulder County, asks whether Boulder, Colorado can sue Exxon Mobil and Suncor Energy under state law for damages tied to climate change, or whether federal law preempts those claims entirely. It's scheduled to be the very first case argued when the justices open their new term on Oct. 5.

In a brief letter sent Monday to lawyers on both sides, Supreme Court clerk Scott Harris wrote that Alito "has determined that he will not continue to participate in this case." The letter offered no further explanation.

An About-Face

The move is a striking reversal. Earlier this year, a Supreme Court spokesperson told reporters that Alito did not need to step aside because he held no financial stake in either Exxon Mobil or Suncor, the two companies actually named in the suit. Alito's most recent financial disclosure shows he does not own those two stocks directly — but he does hold shares in roughly two dozen other companies, including oil majors ConocoPhillips and Phillips 66.

Watchdog groups had argued for weeks that those holdings created an appearance of conflict given how directly the outcome could affect the broader industry's exposure to climate lawsuits nationwide. Consumer Watchdog went further, alleging Phillips 66 and ConocoPhillips had privately flagged the litigation as a material financial risk in filings, while industry trade groups briefed the justice's circle on the stakes.

SUNCOR AND EXXON MOBIL WILL NOW ARGUE THEIR CASE BEFORE AN EIGHT-JUSTICE COURT

The underlying fight traces back to 2018, when Boulder County and the city of Boulder first sued the two energy giants, accusing them of deceiving the public for decades about fossil fuels' role in climate change. Colorado's Supreme Court sided with Boulder in a 5-2 ruling last year, rejecting arguments that federal law wipes out the local claims. The oil companies appealed to the U.S. Supreme Court, framing it as a question of whether a single county can effectively set national — even global — energy and emissions policy through a state courtroom.

What's Next

With Alito out, the case will be argued and decided by the court's eight remaining justices, raising the possibility of a 4-4 deadlock that would leave the Colorado Supreme Court's pro-Boulder ruling in place without setting a nationwide precedent. A decision or split is expected sometime after oral arguments on Oct. 5, with dozens of similar municipal climate suits around the country watching closely for a signal on whether they can proceed.