UK Athletics will reluctantly allow sprinter Dwain Chambers to compete in this weekend's British trials for the world indoor championships.
The 29-year-old, who admitted using the designer drug THG (tetrahydrogestrinone) and served a two-year ban after failing a dope test in 2003, will run in the 60 metres at Sheffield.
"He will be allowed to race but it's through gritted teeth," a UK Athletics spokesman said. "Legally we have no right to stop him."
UK Athletics were opposed to allowing Chambers run in the trials because he has not been regularly drug tested over a 12-month period but world governing body the IAAF has said he is free to compete.
The winner of the trials is selected automatically for the world championships in Valencia on March 7th-9th with the second spot for each event at the discretion of UK Athletics.
Chambers, who tried to forge a career in the NFL last year, is third in the British rankings after running 6.60 seconds in Birmingham last weekend.
His lawyers had threatened legal action if UK Athletics had barred his participation in Sheffield.
UK Athletics chief executive Neil de Vos said he was disappointed with the outcome, saying it did nothing to restore the credibility of a sport rocked by the Balco scandal and the recent imprisonment of Marion Jones.
"To maintain the public's full confidence in our athletes and in the sport in general we want to ensure beyond doubt that all athletes wishing to compete under the Union flag are drug-free," he said in a statement.
"Our view is that all established athletes must participate in the out-of-competition testing programme for a continuous 12 months prior to competing for GB. Dwain is not in that position.
"However, we recognise that we do not have sufficiently strong legal grounds to refuse him an invitation given our published invitation policy. Reluctantly therefore, Dwain Chambers has been informed he is permitted to participate."
Chambers, stripped of his 100m gold medal from the 2002 European Championships, made a brief return to athletics in 2006 and was part of Britain's winning 4x100m relay team at the European Championships in Gothenburg.