2. Nick Diaz (3)
Technically, Nick Diaz has failed 3 drug tests, but they have all been for marijuana. USADA has recently informed Nick and the UFC of another potential failure, although this failure is for rather unique reasons.
USADA is claiming that Nick has not been where he said he was going to be on 3 occasions, preventing them from testing him. Nick not being where he is supposed to be has sort of been an issue throughout his career.
He tested positive for marijuana after his Pride 33 fight with Takanori Gomi. The NSAC believed he was high during that fight as well. Nick flunked a drug test after his interim welterweight title fight with Carlos Condit at UFC 143, and again after his UFC 183 fight with Anderson Silva. All failures were for marijuana.
