Irish trainer Willie Mullins has lost his appeal against the disqualification of Be My Royal from first place in the 2002 Hennessy Cognac Gold Cup.
Mullins won the 2005 Grand National with Hedgehunter
He had said the decision to disqualify the horse, after a positive test for morphine, was "a serious injustice".
A High Court judge ruled that the Jockey Club appeal board's decision to uphold the disqualification was "not amenable to judicial review".
Mullins was not fined but was ordered to pay £5,000 in legal costs.
And he must make an an interim costs payment of £35,000.
Mullins is now considering whether to transfer his legal action to the Queen's Bench Division of the High Court so that he can pursue his claim under private law.
Other outstanding costs will be decided after he has applied to transfer his action early next month.
Mr Justice Stanley Burnton gave his ruling despite accepting Mullins was not responsible for the positive test.
"Morphine may be found in a horse entirely innocently," he said.
"It was accepted by the Jockey Club that the morphine found in Be My Royal resulted from contaminated foodstuff, and that the claimant bore no blame."
Mullins, one of jump racing's top trainers, landed the 2005 Grand National with Hedgehunter and trained Florida Pearl to win the King George VI Chase and a record four Irish Hennessy Gold Cups.
Dismissing Mullins' application for judicial review, made on the basis that the case raised important issues of public law, the judge said: "Review of the disciplinary decisions of the Jockey Club and its organs is a matter of private law, not public law."
The ruling is an important one for all sporting bodies, who have long been considered "private".
Be My Royal was retired just a week after the Newbury race when he suffered a serious injury in his next outing, but was in action for trainer Tom George last season after successful treatment.
The horse came first in the Hennessy at odds of 33-1 but Gingembre was later declared the winner after a test revealed small traces of morphine in Be My Royal's urine.
At a two-day hearing earlier in the month, Tim Kerr QC, for Mullins, said many in the sporting world "would regard being robbed of the achievement of winning the Hennessy Gold Cup as far worse than a breach of any human right - short, perhaps of the right to life".