The chairman of the British Olympic Association, Colin Moynihan, has urged the Court of Arbitration for Sport to reject a challenge to their policy of a lifetime Olympics ban for drugs cheats.
The World Anti-Doping Agency (WADA) has brought a case against the British Olympic Association (BOA), which is the only sporting body to impose such a ban, claiming that it contravenes their anti-doping code.
A decision in WADA's favour could see Britain's former European 100m champion Dwain Chambers and cyclist David Millar eligible for selection for this year's Olympics in London.
Chambers, who won bronze in the world indoor 60m on Saturday in Istanbul, was banned for two years after testing positive for the anabolic steroid THG in 2004 while Millar has also served a doping ban.
Moynihan, a former sports minister who coxed Britain's men's eight to rowing silver in the 1980 Moscow Olympics, said the BOA had a "strong case" and insisted the by-law was fair.
"I think we have taken this very seriously and we are cautiously optimistic that we can put a convincing case forward," he said, as the court prepared to hear arguments from both parties on Monday.
"We have been working pretty hard to do that and we are clear that there is no room in Team GB for people who have knowingly cheated through the use of drugs."
He added: "We have to make sure that the Olympics is a big celebration of sport -- and not a competition between chemists' laboratories."
Moynihan accepted that both Chambers and Millar had shown remorse for their actions and actively campaigned against drugs in sport since their ban but maintained that to scrap the BOA by-law would send the wrong message to budding athletes.
"Those kids need to know that if they reach the top, the Olympics will be clean and that's what we are fighting to do," he added.
The court is due to give its ruling next month.