The sprinter Justin Gatlin is a tailor-made stand-in for the doping ills of track and field.
He served a four-year suspension after testing positive for steroids. He came back and continues to run fiercely in his 35th year, laying down the fastest times ever for a runner his age. Last weekend, in London, he spoiled the retirement run of the great Olympic champion Usain Bolt, whom some writers revere as the symbol of a clean sport. Gatlin ran 9.92 seconds in the 100 meters on Saturday night at the world championships, and took the gold medal.