The British Olympic Association have lost a court case to keep their lifetime ban for drugs cheats.
The Court of Arbitration for Sport (CAS) will tomorrow announce their decision that the BOA's bylaw does not comply with the World Anti-Doping Agency's (WADA) global code, sources with knowledge of the case have confirmed to the Press Association.
The outcome means sprinter Dwain Chambers and cyclist David Millar will have their lifetime bans lifted to allow their selection for Team GB for the London 2012 Games.
CAS rulings are not always cut and dried in favour of a single party, but it is understood this ruling is unequivocally in favour of WADA.
The BOA's response will be to accept the defeat, with the first action to formally remove the bylaw at a full board meeting. That will then open the way to allowing UK Athletics to select Chambers in July, and British Cycling to do the same with Millar in June.
The two athletes had been subject to the lifetime rule for after being banned for doping offences eight years ago. Shot-putter Carl Myerscough would also be eligible for selection.
The BOA will now concentrate on their proposals to change WADA's global code on doping.
They have proposed a minimum four-year ban for a first serious doping offence, including missing one Olympics, with national Olympic committees having the autonomy to have tougher sanctions if they so choose including a lifetime ban.
Any such agreement would not come before the London Games however so would not affect Chambers' and Millar's participation.
Most anti-doping experts believe that it is more likely that WADA will agree to change the new code to increase the length of a ban for a serious offence, but will stop short of allowing different Olympic committees to have different sanctions.
Chambers tested positive for the designer steroid THG in 2003 and was banned for two years.
Millar admitted to taking the blood-boosting agent EPO and he too was banned for two years.
Both athletes have since worked closely with the anti-doping authorities to help them crack down on drug cheats.
Chambers has detailed exactly how he took the steroids to try to avoid detection while Millar is now one of the athletes advising WADA on their methods.
The ruling will be welcomed by former Olympic triple jump champion Jonathan Edwards who said last week it was time for it to be ended.
Edwards said: "Athletes should get a second chance. But two years is simply not enough. The world needs to unite and introduce four-year bans."
The CAS ruling has been widely expected since the International Olympic Committee lost a similar case in November after their Osaka rule - banning drugs cheats from the next Olympics even if their suspension was completed - was challenged.
The case was brought by the US Olympic Committee on behalf of their 400m runner LaShawn Merritt.
The BOA said in a statement: "The British Olympic Association can confirm that today, it has received from the Court of Arbitration for Sport the written decision in the arbitration between the BOA and the World Anti-Doping Association (WADA).
"As the decision is to be announced first by CAS, and out of respect for CAS and the Arbitration Panel, the BOA will be offering no comment today."