Former Racing Victoria chairman David Moodie did leak information during a wide-ranging inquiry into the misuse of cobalt, a court has heard.
Racing Integrity Commissioner Sal Perna's investigation report identified numerous leaks, his barrister Melinda Richards SC said.
She said the critical leak was the provision of information by Moodie, then an RV board member, to his trainer Peter Moody that two other trainers also had horses that had tested positive for cobalt.
Moodie maintains he did not name Mark Kavanagh and Danny O'Brien when he told Moody about the unsubstantiated rumour.
But Richards said he identified them sufficiently for Moody to call them within minutes of his January 2015 phone call with Moodie.
"It was a leak from a person who was a director of the board," Richards told the Victorian Supreme Court on Tuesday.
The information came from a journalist, meaning there were earlier leaks that were also investigated by Perna, the court heard.
"The initial leaker was identified but that doesn't mean he was the only leaker," Richards said.
Perna determined Moodie was not the original source of the January 2015 leak about positive cobalt swabs for the Kavanagh and O'Brien horses.
But he found Moodie inappropriately disclosed information to Moody, compromising or potentially compromising the investigation's integrity, and misled Racing Victoria's integrity council and board about it.
Moodie, who resigned after Racing Victoria considered the confidential report, wants Justice Kevin Bell to quash Perna's findings.
Moodie's barrister Simon Wilson QC has said Perna reframed a simple request for information about the leak into a full-scale investigation and prosecution of the prominent racehorse owner and breeder.
"This former policeman has gone on an absolute frolic of his own in terms of enlarging it, no doubt perhaps to justify his position or show how important he is," Wilson said.
However Richards said Perna acted without fear or favour after being asked to investigate a very serious integrity matter involving the chairman of Racing Victoria.