Was the duck hunt a conflict of interest?

At the center of the dispute over Supreme Court Justice Antonin Scalia's controversial duck-hunting trip is a question only one person can answer.

The issue isn't whether the private hunting trip with Vice President Dick Cheney compromised the justice's ability to be fair and impartial in a case pending before the high court involving the vice president. No one is challenging Justice Scalia's honesty.

Instead, the question is broader. Did the trip create an appearance of judicial favoritism?

Congressional Democrats, a growing number of newspaper editorial writers, and several judicial-ethics experts say it has. They say the justice must recuse himself from hearing the vice president's case or risk tarnishing the Supreme Court's image and his own.

But the federal recusal law that governs such issues authorizes only one person to decide that question - Scalia himself. Specifically, the relevant law requires a judge or justice to disqualify himself from any case "in which his impartiality might reasonably be questioned."

"It is Justice Scalia himself deciding what a reasonable person would believe," says Richard E. Flamm, author of "Judicial Disqualification: Recusal and Disqualification of Judges." "What matters here is not what some appellate court believes, but what Justice Scalia believes is proper."

The 1974 recusal law is aimed at promoting public confidence in the judiciary in part by putting judges on notice that it isn't enough to act ethically, they must also be seen to be acting ethically. Appearances matter.

At the same time, Congress left it up to each Supreme Court justice to decide when or if recusal is appropriate. It is an important protection to guard the high court against those who might use recusal motions to eliminate a justice they fear will vote against them.

Scalia has already recused himself from one high- profile case this term, which examines whether the words "under God" in the Pledge of Allegiance violate the Constitution's separation of church and state. In that case, the litigant who is challenging the pledge filed a motion charging that public comments Scalia made last year about the Pledge of Allegiance suggested bias. Scalia did not attempt to argue the point, or justify his earlier statements.

The justice has taken a different posture following the duck-hunting episode, actively defending his actions. "It's acceptable practice to socialize with executive branch officials," he told the Associated Press after a recent speech.

Details about the hunting trip are still somewhat sketchy. On Jan. 5, Scalia and Mr. Cheney flew together to Louisiana on Air Force Two. They were among others invited to a hunting camp by a Louisiana businessman. Cheney stayed for two days. Scalia hunted for four.

Judicial-ethics experts say the ride aboard Air Force Two could be viewed as an improper gift from a litigant to a justice. In addition, some say the fact that the justice and a litigant are vacationing together undermines the appearance of judicial impartiality.

Cheney's case involves lawsuits filed by a government watchdog group, Judicial Watch, and the environmental group Sierra Club. Both are seeking disclosure of information about consultations between energy officials and the vice president's Energy Task Force back in 2001. Neither group has filed a motion seeking Scalia's recusal, but Sierra Club officials say they are considering it.

The Cheney case is significant because it involves a broad assertion of executive branch authority to conduct White House affairs in secret. Some analysts say the case could result in a 5-to-4 split, or 4-to-4 if Scalia bows out.

Legal experts say the prospect that a recusal could determine the outcome of a case is one reason Congress left it to each justice to decide whether to recuse.

Not every judicial-ethics expert agrees that Scalia must pull out of the case. Richard Painter, a professor at the University of Illinois College of Law, says Scalia's trip with Cheney "might not have been the smartest thing to do." But he says that in his view, one duck-hunting trip isn't enough to justify recusal. "The general rule is you are not allowed to talk about the case with the judge, but there is no flat prohibition on contacts between a litigant and a judge in a purely social setting," Mr. Painter says.

It would be clear grounds for disqualification if Scalia and Cheney discussed the case while on the hunting trip, he says. But there is no allegation that they did.

Scalia and his supporters say judges have lives, too, and there is nothing improper in maintaining a social life while simultaneously deciding contentious issues.

Still, there is no significant body of case law involving judges who went hunting or fishing with litigants. Some analysts say that is because the vast majority of judges routinely avoid such situations.

"Most judges would not do what Justice Scalia did," says Cynthia Gray, director of the Center for Judicial Ethics at the American Judicature Society in Chicago.

"It is important that the public have confidence that judicial decisions are impartial," Ms. Gray says. "The closer the relationship between a judge and a litigant or attorney, the harder it is for the public to believe in the judge's impartiality."

Leslie W. Abramson, a professor and judicial-ethics specialist at the University of Louisville's Louis D. Brandeis School of Law, agrees. "Judges need to think before they act," he says. "That is not to say that every judge has to be a hermit. But judges are in a special position of trust, and they need to conduct themselves in a way that doesn't raise an issue in reasonable people's minds."