A majority of the Supreme Court on Tuesday appeared open to adopting a constitutional due process rule that would require an elected state judge to recuse in a case involving the interests of a major campaign donor.

But the justices wrestled with how to craft a standard for deciding when recusal is required, without opening the floodgates to recusal motions or allowing the standard to spill over to affect appointed federal judges — including themselves.

The Court heard arguments in Caperton v. A.T. Massey Coal Co. (pdf), a West Virginia case triggered by state Supreme Court Justice Brent Benjamin’s refusal to recuse in an appeal brought by Massey, whose president sank $3 million into electing Benjamin in 2004. Benjamin ended up casting the deciding vote in favor of Massey, tossing out a $50 million fraud verdict against it.

“We have never confronted a case as extreme as this one before,” Justice John Paul Stevens said at one point — one of several comments during the hour that suggested growing concern by justices about the cloud over state judicial systems created by increasingly costly and politicized election campaigns.

Retired Justice Sandra Day O’Connor, who has become an outspoken critic of state judicial elections, was on hand in the Court for the arguments, as if to check her former colleagues’ temperature on the problem.

“There is a financial arms race in judicial elections throughout the country,” Gibson, Dunn & Crutcher partner Theodore Olson told the justices on behalf of Massey’s adversary in the West Virginia case.

To which Justice David Souter replied, “Oh, I think we all recognize that.”

Justice Anthony Kennedy, often a swing vote, seemed to share that view by the end of the hour. Kennedy recoiled when Mayer Brown partner Andrew Frey, arguing for Massey, said creating a due process right of recusal was wrong. Frey said the Constitution’s due process clause was not intended to protect the reputation of the judiciary.

“But our whole system is designed to ensure confidence in our judgments,” Kennedy said. “And it seems … to me litigants have an entitlement to that under the due process clause.”

Kennedy’s embrace of that entitlement, paired with favorable comments by Stevens, Souter, Stephen Breyer, and Ruth Bader Ginsburg, could form a majority in favor of a recusal rule.

At the same time however, Kennedy seemed frustrated at the prospect of drafting a standard that is specific enough so as not to require recusal at the drop of a hat.

“Disqualification for bias will now become a part of the pretrial process,” Kennedy told Olson. “I’m asking you what your standard is.”

Olson argued that a rule requiring recusal if a donation created a “probability of bias” was both workable and necessary to preserve the integrity of the state judiciary. He cited a brief by the Conference of Chief Justices, representing jurists in all 50 states, which calls for a rule taking into consideration the size and timing of the donation, and interests and relationships of the donor, in determining whether recusal is required.

When Chief Justice John Roberts Jr. said “probability is a loose term,” Olson replied that the Court has been able to define “probable cause” in the criminal context. In the context of a judicial election, Olson said an “objective observer” test could be applied to decide if a judge is likely to be biased.

But Frey said the standard would be limitless, especially if it considered whether the judge owed “a debt of gratitude” to the donor. By that standard, state judges could be indebted to a newspaper or a political figure for an endorsement, while federal judges could be said to be indebted to the president who appointed them.

On that point and others, the oral argument occasionally veered toward the personal. Justice Antonin Scalia, who was the sharpest critic of a recusal standard during the hour, said to Olson at one point, “You’ve been around Washington a long time. How far do you think gratitude goes in the general political world?”

Scalia also seized on the problem a recusal standard could pose for federal judges — and justices.

Noting that he was appointed to the Supreme Court by President Ronald Reagan, Scalia said he might be deemed to have the same level of gratitude to Reagan as the West Virginia judge might have to his benefactor. “[Reagan] had a lot of issues coming before me,” Scalia said. Olson answered that with life tenure, federal judges would not be viewed as beholden to their appointing president in the same way that an elected judge would be to a large donor.

Roberts also raised a hypothetical which, whether he knew it or not, cut close to the bone for Olson, the former George W. Bush solicitor general who counts many of the justices as his friends.

Roberts asked whether it would be grounds for recusal if a judge and a lawyer appearing before him were “very close friends” or “were at each other’s weddings.”

Olson replied that was an impractical standard. “If that was a basis for a recusal, you would have to be recusing all the time.”

According to published reports at the time, Kennedy attended Olson’s Napa Valley wedding in 2006.