The British Olympic Association's lifetime ban for drugs cheats has been formally declared unenforceable.

The Court of Arbitration for Sport (CAS) have issued a formal ruling that the BOA's by-law does not comply with the world anti-doping code. The decision will allow sprinter Dwain Chambers and cyclist David Millar to be selected by Team GB for the London 2012 Games.

CAS said in a statement: "The by-law is a doping sanction and is therefore not in compliance with the WADA code. The CAS confirms the view of the WADA foundation board as indicated in its decision. Therefore, the appeal of BOA is rejected, and the decision of the WADA foundation board is confirmed."

A bitter exchange of words followed the announcement, with BOA chairman Lord Moynihan branding the decision by the Court of Arbitration for Sport as "a hollow victory" for the World Anti-Doping Association, who had declared the lifetime ban "non-compliant" with their code.

WADA responded by blasting the BOA for "the many hysterical and inaccurate public statements" from the organisation during the case.

Moynihan said: "This will be seen as a hollow victory for WADA. We live in difficult days when WADA spends time and money reducing those countries which have taken a determined stance against drug cheats in sport, such as Canada, New Zealand and ourselves, to a two-year ban which as Sir Steve Redgrave has said is tantamount to almost saying it is acceptable.

"It is also wrong in our view that all 204 national Olympic committees around the world now have to hand over their selection policy towards drug cheats to WADA or face court action."

Attention will now shift to Chambers and Millar, both of whom are likely to be selected for the Games. UK Athletics, who had supported the lifetime ban, confirmed: "Athletes affected by the ruling are now eligible for the team, in both individual and relay events, and will be subject to the same selection criteria and process as every other British athlete."

Moynihan insisted Chambers and Millar would both now have his full support, but said he could do little if they were targeted by spectators during the Games. He said: "I can't speak on behalf of the crowds at the Games - what I can speak on behalf of is the preparations of Team GB."

The BOA will also push now for tougher bans for doping offenders in the WADA code, with a minimum four-year ban for a serious offence such as taking steroids, which would involve missing at least one Olympics.