Justin Gatlin’s career lay in shreds last night after it was confirmed that the American sprinter will remain banned for drug offences for another two years. The Olympic 100 metres champion of 2004 will be unable to defend his title in Beijing in August, but his influence will be felt through the suspicion now engulfing the sport’s blue-riband event.

Gatlin has been fighting to have the eight-year ban he received in 2006 reduced, but while it was indeed halved by a three-man panel overseen by the American Arbitration Association, his exile further demeans an event that has flirted with the gutter since Ben Johnson rose to notoriety at the 1988 Olympic Games in Seoul.

The Olympics in China will mark the 20th anniversary of Johnson achieving a time of 9.79sec and a lifetime of infamy. He was stripped of his gold medal for testing positive for Stanozolol and was last year trading on his tainted triumph by charging $1,000 (about £500) for interviews.

In July 2006, Gatlin tested positive for a banned substance for the second time and, under antidoping rules, should have received a lifetime suspension. However, he cut a deal with the United States AntiDoping Agency (Usada) by cooperating fully and because of what were deemed the “special circumstances” of his first failed test, namely that he was taking medicine for attention-deficit disorder. Usada called for an eight-year ban, but Gatlin was given the right to appeal.

Yesterday, Bill Bock, the Usada general counsel, said that the four-year suspension, backdated to April 2006, had been set by a vote of 2-1, but the arbitrator who dissented, Chris Campbell, claimed that Gatlin had been discriminated against under the Americans With Disabilities Act. Gatlin may now take his case to the Court of Arbitration for Sport.

It is another depressing story that adds to the problems engulfing athletics in the build-up to the Olympics. Marion Jones’s confession to doping in October ended years of lies, ruined one of athletics’ most notable achievements and left the International Olympic Committee contemplating what to do with the American sprinter’s medals. An up-grade would mean her 100 metres gold from 2000 going to Ekaterini Thanou, the Greek who was second in Sydney but the centre of controversy four years later when she missed a drugs test on the eve of the Olympics and claimed that she had been involved in a road accident. The resulting perjury trial is due to start in June.

Gatlin was coached by Trevor Graham, the controversial coach who kick-started the Bay Area Laboratory Cooperative scandal by sending a syringe of tetrahydrogestrinone (THG), the banned steroid that is hard to detect, to Usada. Graham’s athletes have been at the centre of recent doping history, from Jones to Gatlin to Tim Montgomery. That both Gatlin and Montgomery held the 100 metres world record has added to the burden of clean sprinters trying to escape the dirty laundry of their predecessors.

Gatlin’s former world record of 9.77, achieved in Qatar in May 2006, has been expunged from the history books, along with all his results after the positive test.

He claimed that he had been sabotaged and has denied knowing how the banned testosterone got into his system. The reduction of his ban is a reflection of his willingness to turn whistle-blower and help Usada in its case against Graham, who has been charged with lying to federal investigators. Gatlin, 25, has been training with two American football teams, but he may return to athletics at the London Olympics in 2012 if he is still a competitive figure.

The onus is now on Asafa Powell, the world record-holder, and Tyson Gay, the world champion, to clean up athletics’ showpiece event. Powell lowered the mark to a staggering 9.74 in Rieti, Italy, last year and Gay was the undisputed athlete of 2007, winning three gold medals at the World Championships in Osaka, Japan. Another slashing wound would be fatal to the credibility of the 100 metres and the sport must hope these two men go on to produce an historic rivalry that is built on pure foundations rather than win-at-all-costs self-abuse.

But while some have blamed the US for a perceived leniency in dealing with dopers, Britain has also been blighted by scandal. Dwain Chambers might have been in contention for a sprint medal in Beijing had he not taken THG. Recently, Christine Ohuruogu’s case to overturn her life ban from the Olympics for missing three drugs tests was not helped in some quarters by the 400 metres world champion being signed to Linford Christie’s management company.

The former British sprinter tested positive for nandrolone in 1999 and received a two-year ban, despite vigorously denying any wrongdoing.

Speed bans

Three Olympic champions and a world record-holder have brought shame on the sport’s blue-riband event by testing positive for drugs:

Ben Johnson Stripped of his gold medal at the 1988 Olympics in Seoul after winning the race in world-record time of 9.79sec. Banned for life in 1993 after second drugs offence

Linford Christie Upgraded to silver in Seoul, he took gold in Barcelona four years later, but failed a drugs test while in semi-retirement in 1999

Justin Gatlin Olympic champion over 100 metres in Athens in 2004, world champion at 100 metres and 200 metres in 2005 and a world record of 9.77 in 2006. Now banned for four years

Tim Montgomery Set a world record of 9.78 in 2002, but was banned in 2005 after he was implicated in the Balco affair