A few weeks after the conclusion of the 2007 World Championships, reports began to surface that Mellouli had tested positive for a banned substance at the 2006 U.S. Open, 30 November – 2 December 2006. These reports surfaced because FINA, the international governing body of the sport, had discovered that Tunisian authorities had known about the positive test but had only given him a warning. FINA/WADA rules state that when an athlete tests positive for a banned substance, he or she must be given a 2-year ban from the sport. Accordingly, FINA took the case to the Court of Arbitration for Sport (CAS), demanding stiffer sanction.