The NFL Players Association filed a challenge yesterday with the league's special master, Stephen B. Burbank, contesting the Dallas Cowboys' release of quarterback Quincy Carter, union officials said.

The union apparently will ask Burbank, a University of Pennsylvania law professor who is in charge of resolving disputes arising from the NFL's labor agreement, to order the Cowboys to reinstate Carter and give him back pay.

"We're challenging the Cowboys' grounds for termination of Quincy Carter based on skill and performance," Richard Berthelsen, the union's general counsel, said by telephone. "You don't go from being a starting quarterback on a playoff team to not being one of the top 80 players on the roster."

The Cowboys released Carter, their incumbent starter entering training camp, 13 days ago. He reportedly had recently violated the NFL's substance abuse policy and already was in the program because of a previous failed drug test. Carter reportedly was facing a fine equal to four regular season game checks for his second failed test, and would be suspended for four games by the league if he fails a third test.

The collective bargaining agreement between the league and the players' association prohibits a player from being released because of a failed drug test. Players can be released because of skill and performance. Berthelsen declined further comment on the specifics of the case, citing the confidentiality of the league's drug-testing program.

Union chief Gene Upshaw previously expressed concerns about reports that the Cowboys were conducting independent drug tests on players, which is prohibited by the collective bargaining agreement. Berthelsen declined to comment on that issue directly but said: "A whole host of questions will be asked."

A special-master case differs from the league's usual arbitration process and is a trial-like proceeding that allows for discovery of evidence and depositions. Burbank was appointed by U.S. District Judge David S. Doty, who oversees the NFL's collective bargaining agreement, and any decision that he makes is subject to review by Doty. Burbank's first case as the league's special master came in March when he apparently was prepared to grant the union's request that he declare wide receiver Terrell Owens a free agent, resulting in a hasty settlement that enabled Owens to be traded from the San Francisco 49ers to his team of choice, the Philadelphia Eagles.

Asked what remedy the union will seek for Carter, who has not signed with another team, Berthelsen said: "The traditional remedy for improper termination is reinstatement and back pay. Often by the time these cases are resolved, a player will have found a new team, and it's not required that an employee would go back [to his previous club] if he prevails."

Cowboys owner Jerry Jones has said Carter, 26, was cut because of a series of events, not because of a single development, and he is confident that the move will withstand scrutiny. The Cowboys have told representatives of the league office that they independently test their players for drugs.

Carter was the NFC's 11th-rated passer last season, but he helped the Cowboys to a 10-6 record and a playoff berth.

Quincy Carter led the Cowboys to a 10-6 record and a playoff appearance last season.