Supreme Court Justice Antonin Scalia fired back yesterday at critics of his recent duck-hunting trip with Vice President Cheney, issuing an unusual 21-page memo rejecting demands that he disqualify himself from a case involving Cheney.

Responding to a motion for his recusal filed by the Sierra Club, which is suing for access to records of a White House energy task force Cheney headed, Scalia said the justices have never been required to sit out cases involving friends in government who are being sued in their official capacities. To do so now, he wrote, would set a dangerous precedent.

"[W]hile friendship is a ground for recusal of a Justice where the personal fortune or the personal freedom of the friend is at issue, it has traditionally not been a ground for recusal where official action is at issue, no matter how important the official action was to the ambitions or the reputation of the Government officer," Scalia wrote.

"A rule that required Members of this Court to remove themselves from cases in which the official actions of friends were at issue would be utterly disabling," Scalia added, noting that, historically, justices have frequently been appointed precisely because they are close to the president or other members of an administration.

Scalia's point-by-point rebuttal of the Sierra Club's motion and much of the media coverage of his trip with Cheney was unusual, both because he was not required to explain his decision publicly -- justices rarely do so -- and because of the combative manner in which a sitting justice took on what he called "a good deal of embarrassing criticism and adverse publicity."

Scalia's statement means that he will be on the bench April 27 when the court hears oral arguments in the case, Cheney v. U.S. District Court, No. 03-475. His decision cannot be appealed to the full court because on March 1 the justices issued an order saying that Scalia alone would rule on the Sierra Club motion.

"It is probably over at this point," said David Bookbinder, Washington legal director of the Sierra Club. "Obviously, we are going to consider and think about it, but we think it is probably time for the Sierra Club to move on to the merits of the case against Dick Cheney."

Still, Scalia's memo did not end the debate over his contacts with the vice president and the Supreme Court's recusal procedures generally.

The justice's statement set out "the reasons to stay in the case if one wanted to stay in the case," said Steven Lubet, a professor of legal ethics at Northwestern University who had called on Scalia to recuse. "But one would have a lot more confidence in it if it had been made by the other eight members of the court," Lubet said.

He noted that, although Scalia wrote that his conduct was consistent with friendships such as those between Justice Byron R. White and Attorney General Robert F. Kennedy, and between Justice Robert H. Jackson and President Franklin D. Roosevelt, which did not lead to calls for recusal, those cases took place before the enactment of the federal law on judicial recusal. That statute, cited by the Sierra Club as the basis of its motion, requires judges to recuse when their impartiality might "reasonably be questioned."

Scalia laid out the kind of information about his life off the bench that members of the court rarely discuss, offering his most detailed description yet of his trip aboard Cheney's official plane to a Louisiana duck-hunting camp Jan. 5, shortly after the court agreed to hear the case.

According to the memo, Scalia has spent part of the Supreme Court's past five annual winter recesses duck hunting in Louisiana on the property of Wallace Carline, an oil services entrepreneur whom he met through mutual friends.

The idea of bringing Cheney to Carline's camp came from Scalia, who suggested that Carline invite the vice president after Scalia, during a December 2002 visit to Carline's hunting camp, "learned" that Carline was a Cheney "admirer." Scalia himself conveyed Carline's invitation to Cheney a few months later, and Cheney accepted -- offering Scalia a ride to Louisiana aboard his official Gulfstream jet, according to Scalia's account.

But, Scalia wrote, this was done merely for convenience, and he did not benefit financially from the use of Cheney's jet, because he and his son and son-in-law, who also flew with Cheney, ended up buying round-trip commercial tickets to secure a return flight.

At Carline's camp, Scalia and Cheney were part of a group of 13 hunters who slept two or three to a room, except for Cheney, who had a room to himself, Scalia wrote. "It was not an intimate setting," Scalia wrote, noting that he and Cheney were never alone together and did not discuss the case. He took particular issue with newspaper editorials that had suggested he and Cheney actually waited for ducks together in the marshes, noting that "[a]s it turned out, I was never in the same blind with the Vice President."

Cheney left the hunting camp on Wednesday, Jan. 7. Scalia stayed there with his son and son-in-law until Friday, Jan. 9, when they flew back to Washington.

In its motion, the Sierra Club argued that Scalia's trip might appear improper to a reasonable person, citing the newspaper editorials and editorial cartoons and even a monologue by comedian Jay Leno that chided or mocked Scalia.

But Scalia, citing what he said were errors in a dozen newspapers' accounts of his trip, wrote that "a blast of largely inaccurate and uninformed opinion cannot determine the recusal question."

Bookbinder said he was "not sure" Scalia's memo "cures the underlying problem of an appearance of impropriety. No one accuses him of improper conduct; it's the appearance.

"He should have released this stuff in January and then not blamed the press for not writing facts, when neither he nor the vice president would tell them," Bookbinder added.

Justice Antonin Scalia responded to a motion by the Sierra Club.