Nicola Gobbo ranks helping police bring down a world record import of ecstasy in tomato tins as her number one "most significant crime or arrest".
Jan Visser, one of the convicted crooks caught up in the infamous plot, sees her involvement as his ticket to freedom after years behind bars.
He is representing himself in Victoria's Court of Appeal, trying to overturn his conviction and an 11-year jail sentence for importing 15 million pills from Italy in 2007.
He maintains he thought it was illegal tobacco or "chop chop" and he was helping the syndicate avoid tax.
Australian Federal Police and Customs were behind the tomato tins drug bust, but the initial tip came from Victoria Police via Ms Gobbo, the prominent gangland lawyer turned police informer.
The double-dealer known as Lawyer X passed on a shipping document about the 4.4-tonne import to her police handlers, having been handed them by the plot's mastermind, Rob Karam.
Commonwealth prosecutors say there's no way they could have disclosed Ms Gobbo's involvement in the investigation because they didn't know about it until years later.
But Victorian Court of Appeal Justice Robert Osborn says if there was deliberate strategy to keep the joint investigation separate from prosecutors, it seems unfair.
"In this situation it may be argued what occurred was objectively unfair ... albeit there was no fault on the part of either the CDPP or AFP," he said.
Visser is arguing he didn't receive a fair trial because the Commonwealth Director of Public Prosecutions and Australian Federal Police failed to disclose information including Ms Gobbo's involvement, and that the prosecution was malicious.
He also has statements from co-importers Pasquale Barbaro and Saverio Zirilli supporting his claim he thought it was tobacco, with both admitting they "never stated to Jan Visser that the container content was drugs".
Visser argues he could have had the Karam shipping document excluded as evidence, and challenged listening device evidence on the basis police obtained warrants for them four days before they knew the shipment contained drugs.
He also would have called Ms Gobbo as a witness, without worrying she'd say anything against him because he had evidence "she had no idea who I was".
Crown prosecutor Rowena Orr said the vast majority of what Visser said should have been disclosed wasn't known to prosecutors or the AFP, and any additional evidence would not have changed the trial outcome.
She admitted crown prosecutor Krista Breckweg knew in 2011 that Ms Gobbo was an informer and had informed against at least one client, but Ms Breckweg only had a "limited role" in this case.
No one directly involved knew until January 2015, almost eight months after Visser was convicted, she said.
Thirty-two people were jailed over the drugs, including Visser and Karam. Barbaro, the syndicate leader, received a life sentence.
The appeal continues on Wednesday.