Keith Dalgleish became the first rider to fall foul of new Jockey Club procedures when he failed a breathalyser test at Redcar today.
Officials at Portman Square confirmed that the rider had been stood down for the rest of the day for "safety reasons" after two checks revealed the jockey tested positive above the permitted threshold.
However, before any disciplinary action is taken against the rider, a urine sample subsequently given by Dalgleish will have to be analysed, Jockey Club director of public relations John Maxse said.
If the sample did not show an alcohol level above the threshold then disciplinary action would not be taken, Maxse added.
The new regulations concerning the use of breathalysers came into force for the first time at Brighton on July 17th.
Dalgleish, who is principally employed by Middleham trainer Mark Johnston, has ridden 57 winners so far this season, including one at Royal Ascot courtesy of Johnston's Fantastic Love.
The young Scot earned many plaudits for his ride on that occasion, not least from Johnston, who described him as a possible championship contender one day.
Meanwhile, representatives of the riders believe it is up to the Jockey Club to restart negotiations, which are at a stalemate, to resolve the bitter dispute over the mobile phone restrictions.
Michael Caulfield, chief executive of the Jockeys Association, has already indicated his desire to have more talks with racing's regulators "without delay".
"We are keen to talk but I'm not so sure we are going to get anything back," he said.
"I think the industry is expecting them to do something."
However, there is no meeting currently planned between the parties concerned.
The row between the jockeys and the sport's regulators reached boiling point when the riders boycotted Sunday's fixture at Sandown, which caused its cancellation.
The disagreement erupted when the Jockey Club banned riders from using their mobile phones on racetracks from September 1st in the wake of a high-profile corruption court case which revealed that privileged information was being passed by phone.
When asked if they were going to boycott any future meetings Kevin Darley, joint-president of the Jockeys Association, said on attheraces: "For the time being it was a one-off protest.
"Hopefully the Jockey Club have got the opportunity to go back to Michael Caulfield to arrange another meeting so we can, I hope, get it tidied up sooner rather than later."