Trainer Darren Smith has lost his appeal against a 15-year ban over cobalt offences.
The Newcastle horseman was disqualified by Racing NSW in March after he was found guilty of 42 cobalt-related charges.
His legal counsel had argued cobalt was not a prohibited substance because there was no threshold in place when it was administered by Smith.
But the Racing Appeals Tribunal sided with Racing NSW stewards who relied on the rule prohibiting any substance which alters the blood pattern of a horse.