A number of top American track and field stars have enrolled in a special U.S. Anti-Doping Agency (USADA) program aimed at proving they are clean and restoring some credibility to that sports program in this country. The roster of participants, who volunteer for a number of tests—both urine and blood—includes: Tyson Gay, the country's best sprinter, who won double gold in the 100 and 200 meters at the 2007 world championships in Japan; Allyson Felix, the successor to Marion Jones as America's top female sprinter and winner of the gold medal in the 200 meters at the 2007 worlds and a silver, as a 19-year-old, at the 2004 Olympics in Athens; and Bryan Clay, the country's top decathlete and winner of a silver medal at the Athens Games.

One has to credit these athletes, who, recognizing that cheating by elite American stars has tarnished their sport into virtual irrelevance in their country, are trying to find a new path. But they face a daunting task if they hope to rehabilitate their sport's image. Recent history has taught us that the simple fact that an athlete denies ever having tested positive for drugs is no proof that he or she doesn't use them.

"I have been tested repeatedly and never tested positive for drugs" is the familiar refrain of some of America's biggest stars—including Marion Jones and Barry Bonds—who find themselves the target of drug allegations. Jones can still make that claim today, despite the fact that she is now in prison for lying to federal investigators and has forfeited all five medals from her triumphant Sydney Olympics. Bonds can make that claim too, though he is on the baseball sidelines, still waiting for a team to give him a contract and looking ahead to a federal trial on multiple charges of lying to a federal grand jury about his use of steroids.

Antonio Pettigrew is another former U.S. Olympian who has never tested positive for drugs. A member of the American gold medal 4x400 relay team in Sydney, Pettigrew has been a mainstay of the U.S. track team. He was a member of winning relay teams at three successive world championships from 1997 to 2001 and ran a leg on the relay team that set the world record in 1998. Off the track he has been a leader and role model for athletes, serving as an officer on the USA Track and Field's athletes' advisory committee and as an athlete representative to the USOC. Pettigrew is currently an assistant coach at the University of North Carolina.

But last week Pettigrew was forced to shed the "I have never tested positive" defense and, testifying under oath in the trial of his former coach, Trevor Graham, tell the painful truth: that Pettigrew used illegal drugs for four years, from 1997 to 2001: human growth hormone to build up strength and EPO to increase endurance. While some of his gold medals will stand because they extend back beyond the eight-year statute of limitations, his 2000 Olympic gold and those of his relay teammates are in jeopardy.

Jerome Young, a teammate of Pettigrew's in the Graham stable, was banned for life for two doping offenses and stripped of the Olympic medal, though a sports arbitration court allowed his teammates to keep theirs because there was no evidence that he was doping in Sydney and he did not run in the finals.