Jockey Frankie Dettori is set to face a French horse racing inquiry on Tuesday after testing positive for a banned substance in September.
Dettori, 41, is due to appear before the medical committee of France Galop.
He tested positive at Longchamp racecourse on 16 September for a substance which his solicitor has said is not "performance enhancing" .
A separate stewards' committee meeting may be held later, and it is not clear when any verdict will be known.
Dettori could face a ban of several months if he is found to have breached the rules. Any suspension would apply worldwide.
He gave a positive test at a Sunday meeting which was a day of major trials for October's Prix de l'Arc de Triomphe meeting.
The British-based Italian jockey had four rides at Longchamp on that day.
Dettori rode Marco Botti's Joshua Tree to third in the Qatar Prix Foy, while the John Hammond-trained Sarah Lynx trailed home last in the Prix Vermeille.
He was then beaten by a head into second on the Godolphin-trained Farhh in the Prix du Moulin and was third for his former employers on Willing Foe in the Prix Gladiateur.
France Galop, the rulers of French racing, have not commented on proceedings and in keeping with similar previous cases, they have not issued a statement before the hearing.
Last month, three-time champion jockey Dettori announced he was to split with Sheikh Mohammed's Godolphin operation after an 18-year association and go freelance from 2013.
Dettori, who rode all seven winners on the card at Ascot in September 1996, has won 14 British Classics, including the Epsom Derby on Authorized in 2007.
He is also a three-time winner of France's prestigious Prix de l'Arc de Triomphe, on Lammtarra in 1995, Sakhee in 2001 and Marienbard the following year.