Former Racing Victoria chairman David Moodie was denied natural justice in findings that he inappropriately disclosed information during a cobalt investigation, a judge has ruled.

Victorian Supreme Court Justice Kevin Bell found racing integrity commissioner Sal Perna failed to ensure a reasonable apprehension of bias did not arise in his findings against Moodie.

Perna's investigation cleared Moodie of being the original source of the January 2015 leak about two trainers' positive cobalt results, but found the then RV board member inappropriately disclosed information and misled the RV integrity council and board.

Justice Bell on Tuesday said there was a breach of the rules of natural justice when Perna issued a media release about his findings.

The judge made no finding about the scope and extent of the commissioner's powers, saying those matters should be determined in a separate defamation action Moodie has taken against Perna.

The racehorse owner and breeder had argued Perna exceeded his powers.