Jim Best's four-year ban is set to be quashed after the British Horseracing Authority admitted a "fairness" issue in its disciplinary process.
Trainer Best was last month found guilty of ordering conditional jockey Paul John to stop two horses from running on their merits.
But the BHA used solicitor Matthew Lohn on the disciplinary panel.
Lohn was being paid to advise on other matters, and the BHA will not oppose an appeal on "perceptions of fairness".
The case will go back to the organisation's appeal board on 24 May, when Best's conviction is likely to be overturned.
However, the BHA insists it opposes other grounds for appeal and will effectively push for a retrial.
"Having received further details concerning the appeal, and having taken advice, we have decided not to contest the appeal on the grounds of apparent bias. We are still contesting the appeal on other grounds," said spokesman Robin Mounsey.
"Perceptions of fairness in relation to the structure and composition of our disciplinary panels is a legacy issue and we have already agreed to tackle this in our integrity review and have already started to review the structure and composition of disciplinary panels, appeal boards and our licensing committee.
"Our view is the most appropriate next step in this case is for there to be a rehearing before a new disciplinary panel."
The news regarding Best was first reported by the Guardian on Friday.
Privately, the BHA is disappointed details leaked out and insists it can still achieve a conviction, but the new development will have wider implications.
Other cases involving Lohn - who sat on the panel which issued an eight-year ban to Mahmood Al Zarooni in the Godolphin doping scandal - could now be open to challenge.
However, it is thought an Al Zarooni appeal is unlikely as he admitted all the charges against him at the original hearing three years ago.
The BHA has indicated Lohn does not wish to comment. Meanwhile, Best maintains he is innocent of any wrongdoing.