Trainer Peter Moody's camp has lied and made up a nonsense story about a hoof powder causing a racehorse's illegal cobalt level, a tribunal has heard.

But Moody's defence maintains the Caulfield trainer is not a cheat and rejects a stewards' "conspiracy theory", arguing Racing Victoria's own expert now admits Availa could be behind the cobalt reading.

The defence has blamed Lidari's cobalt level - double the allowed threshold after his second in the 2014 Turnbull Stakes - on a stablehand mistakenly giving the horse large doses of the oral hoof treatment for months.

Racing Victoria stewards' legal counsel Jeff Gleeson QC said it was a nonsense story that was months in the making.

"The inconsistencies and absurdities in Mr Moody's Availa story we say are so many in number and so profound in significance that this is nonsense, the Availa story," he said on Thursday.

He said the Racing Appeals and Disciplinary Board should conclude that the defence story was a lie and Moody was central to that lie.

"The only reasonable inference is that the lie is a failed attempt to concoct an innocent explanation for Lidari's cobalt reading."

He said there was no innocent scientific or plausible explanation other than the illicit administration of cobalt.

Defence counsel Matthew Stirling said Racing Victoria's own expert had changed his evidence from there being only a "fluke" chance of Availa causing the cobalt reading to it being just about beyond reasonable doubt.

"RVL must now destroy the credibility of the Moody witnesses because if they don't their own expert says what they gave the horse would have caused the levels," Mr Stirling said.

Mr Stirling said Moody was truthful and does not cheat, rejecting Mr Gleeson's "conspiracy theory".

"There is no evidence of anything Moody has done either leading up to or at the time of the offending," Mr Stirling said.

"That's critical because the very thing they have to prove is that Moody administered."

Mr Stirling also argued the evidence should be thrown out because stewards made multiple deliberate breaches of contract.

One of the issues involves Racing Victoria overriding the official laboratory's decision not to analyse one of Lidari's urine samples because there was an insufficient amount.

The RAD board will give its decision at a later date with Moody facing a minimum three-year ban if found guilty of administering a prohibited substance.