Trainers Danny O'Brien and Mark Kavanagh will have to wait a little longer to find out if they face time on the sidelines following a submissions hearing on penalty over their long-running cobalt case at the Victorian Civil Appeals Tribunal.

VCAT president Justice Greg Garde has reserved his decision which will be published and made public at a future date.

Justice Garde last year overturned a Racing Appeals and Disciplinary Board decision to disqualify O'Brien for four years and Kavanagh for three,a decision Racing Victoria appealed.

The Court Of Appeal returned O'Brien and Kavanagh to VCAT for a hearing on penalty for presenting horses to race with cobalt detected in post-race urine samples.

Justice Garde had concluded that while there was no doubt cobalt was administered to four O'Brien horses and one Kavanagh racehorse in late 2014, the trainers had no knowledge of it and could not be guilty of the administration.

Damian Sheales, representing the trainers, told the hearing the pair should not be penalised with the case now into its fourth year since the trainers were initially informed of their high cobalt readings in January 2015.

Sheales said it was it was time to draw a line when it came to cobalt and that it was "reverse discrimination".

He said the case was unique and O'Brien and Kavanagh had been put through a lot over the past three years.

"There will always be a stain on them and their businesses," Sheales said.

He said three horses had been successful with another running second which will ultimately lead to the horses being disqualified and the two trainers losing their prize money percentages.

"I hope that will be taken into account," Sheales said.

Jeff Gleeson, representing Racing Victoria, called for a penalty that was "moderate and just" given the significant and high profile breaches.

He said the trainers had brought horses to race with a prohibited substance in their system adding that the image of racing had been damaged.

"To operate as a trainer in Victoria and Australia is a privilege," he said.

"Obligations come with that privilege."