Andre Agassi’s confession in The Times yesterday was certainly shocking. And the Association of Tennis Professionals (ATP), which found evidence of crystal methamphetamine ingestion in 1997, has proved the doziest of police forces in so softly and willingly allowing Agassi to go scot-free. Dozy, self-serving and, as such, very much like many other in-house policing systems in sport.

Who, after all, would want to see their star player bring shame upon themselves and on their sport? If you are promoting tennis and you want to bring fans, television viewers and sponsors to the game, the crystal meth headlines are disastrous. In 1997, the ATP had the opportunity to bury them and it deserves censure for that. But it was by no means operating alone.

We know this because one of the most senior men in the business in the United States told us so. Dr Wade Exum was the director of drug control administration for the United States Olympic Committee (USOC) for nine years to 2000. The end of his time there was ugly and litigious and when it got really dirty, he emptied into the public domain evidence of the culture of cover-up against which he claimed he had been fighting a losing battle.

Exum’s parting shot was the release of documentation that revealed about 100 athletes had failed drug tests, that they should have been banned from competition but instead were allowed to compete in the Olympic Games.

Most damaging in all this was one of the names that he coughed up — Carl Lewis. At the 1988 US Olympic trials, Lewis gave a urine sample that showed he had three banned stimulants in his system. Lewis was asked by the USOC to account for this and he insisted that there was no intent to cheat and that the explanation would be found in an over-the-counter medication that he had taken. And you can see where the USOC was coming from: Lewis was their biggest name and one of their biggest medal hopes, so who wouldn’t want to believe him?

Unfortunately for Lewis, he was let down by the system at the time. If a proper policing system had been in place and if the USOC had not had this extreme conflict of interests, we might be able to trust the judgment and Lewis might not have had this uncertainty leaving such a stain on his achievements.

But there was a lot of untrustworthy stuff in the wash at the time. Hundreds of drug-test results were shredded at the Los Angeles Games in 1984. At the Sydney Olympics 16 years later, the Americans won a gold medal in the men’s 4 x 400 metres relay having fielded an athlete, Jerome Young, who had already tested positive.

Indeed, the Americans were beginning to look so ludicrous that they eventually elected to do the sensible thing — acknowledge that a self-policing USOC was no longer credible and so the responsibility for policing had to be taken away altogether. Instead, the US Anti-Doping Agency was created and the rest of the world could look them in the eye again.

Quite how much cheating of this kind went on in the US and elsewhere we will never know. But the USOC and the ATP have only proved that you cannot be promoters of your sport and its police force simultaneously.

It just so happens that, on December 14, we will finally bring an end to such a conflict in this country. The goal of UK Sport is to deliver gold medal-winning athletes; until now it has also been its own drugs police.

But on that date UK Anti-Doping, a new agency, opens its doors for business. It thus joins the growing number of independent anti-doping organisations that help to give credibility to the fight against cheating, such as the World Anti-Doping Agency (Wada), which has delivered a consistent set of rules and made it infinitely harder to bury bad news.

Yes, we now have a far better, infinitely tighter system. Yet we also still have a conflict of interest. The ATP no longer polices tennis; the International Tennis Federation does. The International Cycling Federation (UCI) is its own police, as is the IAAF, the world governing body of athletics. Likewise many sports.

As it happens, the anti-doping programme at the UCI and the money that funds it make it probably the most comprehensive anti-doping policing system in the world. And the IAAF completed a long, fascinating and hugely expensive investigation last year that busted seven potential Olympic medal-winners on a doping programme in Russia.

But what if, at the end of one of these exhaustive investigations, the IAAF discovered evidence that convicted a really big name, the Carl Lewis of our day? What if that was an athlete of the status of Usain Bolt? That would be absolute catastrophe. And an exceedingly horrible conflict of interests.

Testing times

By Patrick Kidd

• In 2007, Martina Hingis, the former world No 1, was in the second year of her comeback when she tested positive for cocaine during Wimbledon. She was banned for two years and left the sport, vowing not to return. Hingis has repeatedly protested her innocence, saying she would be “terrified of taking drugs”.

• Jennifer Capriati went off the rails after winning an Olympic gold medal in 1992 at the age of 16. The American was arrested two years later for possession of marijuana. She played only one match on the women’s tour over almost 2 and a half years, but rebuilt her career and won three grand-slam titles.

• Richard Gasquet, of France, was suspended in May pending an investigation when he tested positive for cocaine. He was cleared of wrongdoing after explaining that the drug had entered his system after kissing a woman known as "Pamela" at a nightclub.

• Greg Rusedski was the British No 2 when he was tested positive for nandrolone in 2003. In March 2004 Rusedski was cleared after successfully arguing that any excess levels in his system must have been mistakenly given to him by trainers employed by the ATP.

• Mariano Puerta, of Argentina, has twice been banned for drug offences. In 2003 he was suspended for two years, reduced to nine months, after testing positive for clenbuterol, which he said had been part of his asthma medication. In 2005, after reaching the French Open final, he was banned for eight years, reduced to two, after etilefrine, the cardiac stimulant, was discovered in his system. Puerta claimed it had entered him after he used a glass also used by his wife, who was on medication.

• Mark Nielsen, a little-known New Zealander who reached a peak of No 172 in the world, was suspended for two years in 2006 after testing positive for finasteride, which was on the banned list as a potential masking agent. Nielsen had been using an anti-balding medication that contained the substance.