The Supreme Court on Monday referred to Justice Antonin Scalia a request by the Sierra Club that he remove himself from a case involving the vice president because of a duck hunting trip the two men took in January. The request was filed last week. The court said that “in accordance with its historical practice,” Scalia would handle it himself.

The Sierra Club environmental group, which sued Cheney for the task force papers, filed a motion last week asking that Scalia disqualify himself from the case because the January trip had created “an appearance of impropriety.”

It said Scalia’s removal would “restore public confidence in the integrity of our nation’s highest court.”

The justices said in a brief order, “In accordance with its historic practice, the court refers the motion to recuse in this case to Justice Scalia.” It was not clear when Scalia would respond to the request.

He has defended his decision to go on the trip and said his impartiality could not be reasonably questioned.

According to the motion, Scalia and his daughter were Cheney’s guests on Air Force Two for a Jan. 5 flight to Louisiana. Cheney and Scalia were guests of the president of an energy services company on a duck-hunting vacation.

Cheney is being sued by the Sierra Club and another group. They want him to release documents about White House contacts with the energy industry in 2001. The vice president has appealed to the Supreme Court a ruling ordering him to produce the documents.

If Scalia removed himself from the case, it would raise the prospect of a possible 4-4 vote. When the high court deadlocks, the lower court’s ruling — in this case the U.S. appeals court decision that went against Cheney — is upheld.