Justice Samuel Alito recused himself on Monday from Suncor Energy v. Boulder County, and the climate plaintiffs just won their case. Not on the merits. On a procedural courtesy to the radical flank of the bar.

Here is what the Supreme Court’s October argument was supposed to settle: whether state courts may conscript state-law tort claims into a vehicle for punishing energy companies for the weather. The Colorado Supreme Court had answered yes. The Justices were poised to answer no. Instead, by stepping aside, Justice Alito has given Boulder County, and every copycat plaintiff attorney now warming up a complaint, exactly what they wanted — a 4-4 affirmance by silence.

A tie leaves the Colorado court’s preemption ruling in place. It blesses the proposition that a Colorado county can hale an Alberta oil company into a Colorado courtroom and demand damages for sea-level rise in Bangladesh. It tells every ambitious state attorney general, and every trial lawyer running climate-justice Superfund ads, that the courthouse door is open and the federal Constitution is a footnote. The Court’s failure to rule is, in practical effect, the plaintiffs’ victory.

What changed between May, when the Court said Justice Alito did not have to step aside, and Monday, when he did? Not his portfolio. Not the law. The pressure.

In May, Earthworks and Feminist Majority — outfits with no particular expertise in judicial ethics and every particular interest in kneecapping the energy industry — demanded his recusal. The hook was a “Vanguard High Dividend Yield ETF, in which Exxon is the third-largest holding.” Vanguard’s own disclosure puts Exxon’s share of that fund at 2.7%. Two-point-seven percent of a fund that holds roughly four hundred positions is not a financial interest in any party. It is the financial equivalent of owning a fork. The Court’s own spokesperson told NBC that “Justice Alito does not have a financial interest in any party,” and legal counsel advised that “his recusal is not required.”

He was right the first time. He was wrong to change his mind.

There is a duty, and it is older than this controversy. Then-Associate Justice William Rehnquist wrote it plainly in 1972: “A federal judge has a duty to sit where not disqualified which is equally as strong as the duty to not sit where disqualified.” The Supreme Court has no substitute bench. There is no reliever in the bullpen. A 4-4 affirmance is not a hung jury awaiting retrial. It is a judgment, and it is final.

Justice Antonin Scalia made the same point in 2004, when liberal coalitions demanded he step aside from Cheney v. United States District Court because he had gone hunting with the Vice President. “If it is reasonable to think that a Supreme Court Justice can be bought so cheap,” Scalia wrote, “the Nation is in deeper trouble than I had imagined.” Folding under such pressure, he warned, would invite “increasingly silly” demands based on the Washington social calendar.

Justice Alito knew all this. He took Scalia’s side of it once. He should have stayed there.

The threat is not theoretical. It is already here. Every Justice who owns a diversified mutual account — which is to say, every Justice who participates in a modern retirement portfolio — now sits one headline away from disqualification. Every Justice whose spouse donates to a cause, attends a wedding, teaches a class, or sits on a charity board sits one opposition-research packet away from the same. The next case will not be a climate case. It will be an immigration case. It will be a gun case. It will be an agency case. Litigators will find the slimmest thread and pull.

The Court can defend itself in only one place. By refusing the demand.

Justice Alito’s recusal is not, on the face of it, disqualification. It is discretion. He chose to step aside. That is the bad news. Discretion, exercised to appease a partisan constituency, becomes the precedent. The precedent becomes the rule. The rule becomes the weapon.

This Court has nine seats for a reason. Each Justice is one-ninth of the institution. When one steps aside because a coalition letter made the rounds, the institution loses. Litigants lose. The country loses.

Justice Alito should reverse course. If the Court splits 4-4 in Suncor, it should set the case for reargument once a ninth Justice returns. And the next time a partisan coalition sends a letter, the answer should not be a recusal. The answer should be the one Rehnquist and Scalia gave theirs.

No.