A press release from the FEI confirm that Qatar's Sheikh Ali Al Thani and Bassem Mohammed have tested positive for Carboxy-THC, a metabolite of cannabis – a prohibited substance under the FEI’s Anti-Doping Rules for Human Athletes (ADRHA).

The samples were taken on 13 October 2019, the day of the Olympic Jumping Qualifier for Africa & Middle East in Rabat, Morocco, where Sheikh Ali Al Thani and Bassem Mohammed helped Qatar book one of the two Tokyo 2020 team quota slots available. 

According to the FEI, the riders have not been provisionally suspended "as Carboxy-THC is a *Specified Substance banned in competition under the 2019 World Anti-Doping Agency (WADA) Prohibited List". 

Explained in the press release, a specified substance "should not in any way be considered less important or less dangerous than other doping substances. Rather, they are simply substances which are more likely to have been consumed by an Athlete for a purpose other than the enhancement of sport performance. Positive cases involving Specified Substances can be handled with a greater degree of flexibility within the structure of the FEI Regulations."

However, should the positive tests lead to disqualification for Sheikh Ali Al Thani and Bassem Mohammed from the Olympic Jumping Qualifier in Rabat, Qatar’s team quota place would be reallocated to Morocco – first on the reserve list. 

Details on these cases can be found here.