Mr Pakula said the Government could introduce legislation which would give Racing Victoria the powers they have been asking for.
"It's beyond time for minister Napthine to give RVL the powers they've been calling for for two years now," Mr Pakula said.
"The minister continues to stubbornly refuse. It's beyond belief that he would continue after today.
"We've got the Melbourne Cup today which should never, ever be under a cloud."
Mr Pakula said there was "absolutely no reason" to deny Racing Victoria the powers that Queensland Racing and New South Wales Racing have already got.
"I do think this is prevarication bordering on negligence," he said.
The news of the investigation caused Oliver to be sacked from the Lloyd Williams-owned Green Moon in the Cox Plate and My Quest For Peace in the Caulfield Cup.
He later picked up the ride on 2010 winner Americain, which never really got into the race, in the event.
Mr Pakula said the Opposition had made it clear if the Government brought forward legislation to increase Racing Victoria's powers, the Opposition would pass the legislation "without hesitation".
Oliver posted a Melbourne Cup Day win when Walk With Attitude won the Lexus Hybrid Plate.
-AAP