Doping authorities should bring their rules into line with the International Olympic Committee to prevent convicted cheats competing at the Olympics, former sprint champion Michael Johnson said on Wednesday.
The Court of Arbitration for Sport (CAS) cleared the way in October for dozens of convicted dopers to compete at the Games when they rejected an IOC eligibility rule as invalid.
The rule, which was introduced in 2008, banned athletes from competing at the next Olympics if they had served a suspension for doping of six months or longer.
CAS said the Olympic ban was not in line with the World Anti-Doping Agency's (WADA) code.
"I think the IOC is going to have to go back and work with WADA to get that (eligibility) rule as part of the WADA code," Johnson, a four-time Olympic gold medal winner, told Reuters at a charity event in South London.
"Once that is in place I think everybody will be a lot happier."
The CAS ruling has opened the door for Olympic 400 metres champion LaShawn Merritt to compete at the next Games in London in 2012.
The American was handed a 21-month ban for testing positive for a banned substance in 2009 and 2010, but has since returned to competition and was a double medallist at the world championships in South Korea in August.
The International Association of Athletics Federations estimated around 50 track and field athletes could be affected by the CAS verdict.
"I think that their ruling makes sense," added Johnson. "(They said) it's not fair to ban a person and then ban them again once they have already served their punishment.
"But I think that all of those people sitting on that board probably felt like they wish it were fair, because I think they all think as I do, that it is a good thing having an athlete who has been caught cheating miss an Olympics.
"They probably felt like their hands are tied."
Critics of the IOC eligibility rule said it acted as a double punishment, with athletes serving suspensions and then being forced to miss the Olympics.