Legal experts believe Dwain Chambers has a 50-50 chance of overturning the rule that bars any British competitor found guilty of a serious drugs offence from ever taking part in the Olympic Games. With the disgraced sprinter threatening to challenge this bylaw of the British Olympic Association (BOA), the athletics world has been thrown into turmoil by his unexpected return. Chambers has been picked to run the 60m in the world indoor championships in Valencia next month even though the British selectors want to bar him.

The 29-year-old’s real target is to show that he can win an Olympic medal in Beijing in August without taking performance-enhancing substances, which led to him serving the maximum two year-ban from athletics in 2004 and missing the Athens Games.

However, it is estimated that it would cost him £150,000 should he lose a case in the High Court against the BOA, the only Olympic body in the world that bans drug cheats for life. In 2004 Norway became the last country to abandon a similar regulation.

One leading lawyer, Peter Coyle of Coyle White Devine, puts the odds on Chambers winning at evens. After examining the bylaw, he said the first difficulty was that the High Court does not like to get involved in sporting matters, which it prefers to leave to the ruling bodies. However, it will intercede if it believes a sporting body has acted perversely.“

The next question is whether the bylaw is unreasonable,” says Coyle. “I think it is, because it contravenes the natural justice that once you have served your punishment, you can then rejoin society on an equal footing. The fact that Britain is the only country taking part in the Olympics which now has this bylaw strengthens his case. The High Court might then intervene to set aside the bylaw.”

Chambers will also be heartened by comments from Dick Pound, the outgoing president of the World AntiDoping Agency (Wada). He criticised the BOA’s rule because it does not fall within the Wada code, ratified by Britain.

However, the BOA will argue that Chambers knew of the bylaw when he began taking a cocktail of drugs, including the designer anabolic steroid tetra-hydrogestrinone (THG). He has admitted he was using THG when he won the European 100m title in Munich in 2002.

Mel Goldberg, a well-known solicitor and the chairman of the British Association for Sport and the Law, says: “Chambers has an arguable case. He has a reasonable chance of winning. After all, he has already been penalised with a two-year suspension. It would be a very interesting case.”

Lawyers say Chambers would be best advised not to appeal direct to the BOA because the three grounds for appeal are not relevant in his case. These are that the offence was minor; that there was a significant fault or negligence in the doping offence; or that there were significant mitigating circumstances.

Nor should he go to the Court for Arbitration in Sport in Lausanne, because the Beijing Games might have finished by the time the case is held. The High Court is the fastest, although most expensive option, and the case could be heard there within several weeks.

The BOA points out that the bylaw was introduced in 1992 with the full backing of the competitors. Martin Cross, the Olympic rowing gold medallist who was chairman of the Athletes Commission at the time, says: “We acted in response to the overwhelming feeling of the competitors themselves. The athletes felt they were powerless and needed some protection.” In a 2006 survey, the athletes were 95 per cent in favour keeping the regulation.

Another British athlete also banned from participating in Beijing is the shot-putter Carl Myerscough, who was selected alongside Chambers for the world indoor championships. He will be watching his teammate’s legal progress intently.

Chambers’s main problem is how to fund his challenge. He might find lawyers prepared to waive their fees because of the high-profile publicity if he wins the case, but he would need the insurance of a wealthy benefactor in case he loses.

He is already having to repay more than £100,000 because he has admitted taking drugs while earning prize-money and bonuses from meeting organisers and the International Association of Athletic Federations (IAAF), the world governing body. His chances of fulfilling this obligation have been cut by the announcement last week by the organisers of the main meetings that he would not be invited to their events in Britain and the rest of Europe, such as yesterday’s in Birmingham and one in Ghent, Belgium, next weekend. If he wins any prize-money in Valencia, it will go towards paying off the debt.

Because of his doping suspension, Chambers is receiving no financial assistance for training from UK Sport and is not being paid competition expenses when representing Britain, such as flights and accommodation for the world championships. These are being met by UK Athletics, the national governing body, out of its own reserves. On Friday he trained alone at the Lee Valley centre in northeast London, but only after the UK Athletics-funded competitors had enjoyed exclusive use of the facilities between 9am and 1pm, when the public is not admitted. He even had to pay a £3.90 admission fee.

Eric Shirley, the high performance director at the Picketts Lock complex, has denied that any of the UK performance coaches there are assisting Chambers. Linford Christie, the 1992 Olympic 100m champion who trains another group at Brunel University, was surprised when he was asked whether he had been giving advice. Christie, who used to manage Chambers until they broke up eight years ago, replied: “Why should I have contact with him ?”

He said he was concentrating his efforts on helping Christian Malcolm, another leading sprinter, as well as several promising young athletes. Of the competitors beaten by Chambers in the 60m trials in Sheffield last Sunday, Christie said: “Shame on the athletes. They should go out there and win. There is the lane. Go down it faster. Then we wouldn’t be having this argument.”

Christie is unable to be an official coach to the British Olympic team in Beijing because he himself has been suspended for a drugs offence, when he came out of retirement in 1999 for an indoor meeting and had an adverse finding for nandro-lone, an anabolic steroid subsequently linked to many food supplements. Christie insisted that he was innocent and was cleared by UK Athletics, but the IAAF imposed a suspension.

One person still supporting Chambers is Victor Conte, the former head of the Bay Area Laboratory Cooperative (Balco) in San Francisco, who supplied him with drugs when he went to California in 2002.

Conte subsequently helped US officials with their inquiries into doping in American sports. He claimed last week that he had supplied Chambers with legal supplements last year and spoken to him before and after his victory in Sheffield last weekend. If true, it is scarcely a sensible move by Chambers, who must regret every minute of the day he was introduced to Conte and made the decision to take drugs.

Beating the cheats

- If an athlete tests positive, the case is dealt with by a national federation under the jurisdiction of the International Association of Athletics Federations (IAAF)

- The IAAF suspends athletes with drug offences for a maximum of two years. From January 1, 2009, that penalty will be doubled

- Between 1991 and 1997, the IAAF banned athletes for four years but it cut that in half because of the growing litigation from competitors appealing

- Britain is now the only country which stops disgraced athletes from competing in the Olympic Games, even when they have served their ban.

- Athletes who have returned from drug bans include Ukrainian Lyudmila Blonska, who won heptathlon silver at last summer’s world championships. The disgraced Ben Johnson, right, reached the Olympic 100m semifi nals in 1992 but tested positive again for steroids in 1993 and was banned for life

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