Drug kingpin Tony Mokbel has had one of his drug convictions quashed by the Victorian Appeals Court as he prepares to appeal further judgements including potentially arguing his extradition from Greece was “unlawful”.

Herald Sun court reporter Genevieve Alison told Sky News the decision to quash Mokbel’s conviction on cocaine importation was a “surprise development” in his long running legal battle to walk free.

The appeal is one of many on the grounds what is now being called the ‘Lawyer X principle’ whereby defendants will argue their convictions were tainted by disgraced barrister turned police informer Nicola Gobbo.

Mr Mokbel’s conviction for importing two kilograms of cocaine from Mexico was quashed with his sentence set aside, but the director of public prosecutions conceded there was no point in ordering a retrial given he has already served that portion of his 22-year sentence.

Ms Alison said Nicola Gobbo was informing police of Mokbel’s legal strategies as well as some of his other criminal activity outside charges he was facing while she was his barrister.

“Mokbel and a lot of her other former clients are still waiting for a lot of that disclosure material from police to find out exactly how much she told investigators while she was representing these clients,” she said.

“Even if it was a small amount of information, it was too much in the eyes of the law”.

The convicted drug trafficker is also reportedly looking to appeal a conviction on the grounds that his extradition from Greece was unlawful as he “sought legal advice from Gobbo still trusting her as a trusted legal counsel”.

“So one of the grounds of his upcoming appeals will be that the extradition was unlawful because his lawyer may well have got him into that situation in the first place.”