Graham Gibbons will face a disciplinary panel of the British Horseracing Authority on Thursday after testing positive for cocaine.
The jockey has not ridden since December last year, when he was alleged to have swapped a urine sample with that of another rider, Callum Shepherd, at a meeting at Kempton.
In details released on Wednesday by the BHA, Gibbons is charged with a breach of rule (D)65 "by virtue of the fact that a urine sample taken from him on December 7, 2016 at Kempton racecourse tested positive for benzoylecgonine, a metabolite of cocaine and, pursuant to rule (D)58 and schedule (D)3 Part 1, a banned substance".
A BHA statement went on: "Also, whether he has committed a breach of rule (A)30.1 by acting in a manner prejudicial to the integrity, proper conduct and/or good reputation of horseracing in Great Britain by his actions on December 7, 2016 when he attempted to present another jockey's urine as his own when required to submit a sample for testing purposes."
In a separate hearing, former jockey Dale Swift will face a disciplinary panel after he, too, tested positive for cocaine after a urine sample was taken from him at Southwell in March.
Select any odd to add a bet