Some of the country's most feared gangland criminals are eyeing freedom after their convictions were potentially tainted by the involvement of criminal barrister and police informant Nicola Gobbo, also known as Lawyer X.

Faruk Orman has become the first man to have his gangland conviction quashed over the Victorian legal scandal, after the Court of Appeal found he had suffered a substantial miscarriage of justice in his murder trial.

The overturning of his conviction will offer encouragement to others serving long jail stints after they were convicted in trials where Ms Gobbo played a role — including underworld figure Tony Mokbel.

Royal commissioner Margaret McMurdo and counsel assisting Chris Winneke QC detailed in their opening addresses in February that Victoria Police used at least six people — including Ms Gobbo — who held privileged positions as registered informers.

So far, court documents have revealed it was the work of Ms Gobbo, also known as Informer 3838, that led to one of Mokbel's employees being "rolled" by police, which marked the beginning of the end of the drug kingpin's empire known as The Company.

Sorry, this video has expired Why you should care about the Lawyer X affair

During a series of police operations targeting clandestine drug labs across Victoria, many of Mokbel's main men were arrested, including his brother.

The Director of Public Prosecutions (DPP) believes Mokbel and at least seven of his associates could now have grounds to overturn their convictions.

The details of Ms Gobbo's involvement in those cases was detailed in documents released by the Supreme Court last year.

Two other criminals have also flagged challenging their convictions in the wake of the Lawyer X revelations, with more likely as the scope of the scandal expands.

The seizure of 15 million ecstasy pills hidden in 3,000 tomato tins led to the imprisonment of Rob Karam, Pasquale Barbaro and John Higgs. ( Australian Customs )

Tony Mokbel: serving a 30-year jail term for drug trafficking

Drug boss Tony Mokbel is the most notorious gangland criminal whose conviction has been tainted by the legal scandal.

He is currently serving a 30-year sentence, with a 22-year minimum, for drug trafficking, including 12 years for cocaine smuggling.

Between 2002 and 2006 Ms Gobbo represented Tony Mokbel in seven court hearings.

Lawyer X represented Tony Mokbel in seven court hearings. ( AAP: Julian Smith )

Information she passed onto police included how best to limit his movements while on bail and details of credit card transactions, along with his tactics on how he planned to fight cocaine smuggling charges.

When Mokbel skipped bail in 2006 and fled to Greece, becoming Australia's most wanted fugitive, she continued her contact with him and passed on his plans to fight his extradition to police.

According to the DPP, Mokbel would have thought Ms Gobbo was acting for him, and given she was working for police he could argue he did not receive a fair trial, as he did not have independent counsel.

It is also possible for him to challenge his convictions after an illegal extradition.

The snitch

A main piece in the puzzle for police was the arrest of one of Mokbel's employees, who was central to his drug empire.

The man cannot be named for legal reasons, but he had a close relationship with Ms Gobbo.

But his trusted friend and confidant, Ms Gobbo, told police the man was the one to "roll" if they wanted to get Tony Mokbel's brother, Milad Mokbel.

When the employee was arrested and charged by police he called his lawyer, unaware that she would then pass on information about his other activities, leading to further charges being laid against him

When he was again arrested during a raid, the employee called Ms Gobbo, not knowing she had been the one to give police the address.

She was his lawyer when he agreed to snitch on the rest of the Mokbel cartel.

The Chief Commissioner agrees that given the role his lawyer played in his capture, the snitch could argue an abuse of process had occurred and have his conviction quashed.

Tony Mokbel's close associates, in prison over a shipment of ecstasy tablets weighing more than 4.4 tonnes, are eyeing freedom. ( Supplied )

Mokbel associate #1: four years' jail for drug offences

Associate #1 was arrested in police raids and received a four-year sentence for drug offences.

Ms Gobbo led police to the clandestine drug lab after being given the address and told police she hoped he would be arrested alongside Mokbel.

Following associate #1's arrest, Ms Gobbo appeared in court to represent him on four occasions, but she denied she ever double-crossed him.

A Supreme Court judge believed the man could argue a conflict of interest because it was his own lawyer who led police to him — in legal terms, he was denied independent advice.

The boss's brother Milad Mokbel: 11 years' jail for drug trafficking

Tony Mokbel's brother, Milad Mokbel, was charged with help from an associate. ( ABC News )

With the cartel's snitch now helping police, Milad Mokbel was also charged with trafficking methamphetamine and dealing with proceeds of crime, after a police sting.

Milad Mokbel turned to the trusted Ms Gobbo, calling her after his arrest.

She also later provided him with legal advice when his wife, Renata Mokbel, ended up in trouble.

Ms Mokbel had put up surety for her brother-in-law, landing her in hot water when he fled the country.

Tony Mokbel would later name his baby, who was born whilst he was hiding, after his sister-in-law Renata Mokbel, who ended up in prison.

In 2008, Milad Mokbel was sentenced to 11 years in jail for drug trafficking and blackmail offences.

While Milad Mokbel pleaded guilty to the charges, a Supreme Court judge believes the drug trafficker had a right to know how the evidence of one of his own men was procured, making his conviction unsafe.

Mokbel associate #2: Three-year suspended sentence for trafficking

In a phone call to Ms Gobbo in August 2005, Detective Paul Rowe told her they were holding "a mate" of hers.

The man, who can't be named for legal reasons, had been set up by the snitch, who had worn a wire while discussing drug-related plans.

While Ms Gobbo claims she didn't know about their plans discussed that day, she did know he was involved in drug activities.

In March 2006, Ms Gobbo met her client at Melbourne's Wheat Cafe and gave him a phone to organise the delivery of three kilograms of MDMA.

Associate #2 would later turn Crown witness and implicate Tony Mokbel and others.

Ms Gobbo named the man on a list of criminals she had helped police catch.

The DPP said the fact he did not know the snitch was working for police could lead to his conviction being quashed.

Given Ms Gobbo was a police informer at the time she represented the man, she may also have breached her professional responsibilities and duty of loyalty to him.

Lawyer X convinced Kamel Khoder to plead guilty. ( ABC News )

Kamel Khoder: Mokbel associate and money launderer

Police handlers directly asked Ms Gobbo to provide information on Kamel Khoder.

When he was arrested the following year on fraud charges, it was she who persuaded him to plead guilty. Khoder was handed a two year wholly suspended sentence.

Again, Ms Gobbo listed him as one of the criminals she had helped police convict, but later argued in court the charges against Khoder had not come from anything she told police.

The DPP said Khoder could argue a miscarriage of justice given his lawyer was, firstly, tasked with providing information to police about him and then persuaded him to plead guilty.

Pasquale Barbaro was jailed in 2012 over the massive tomato tins drug bust. ( Supplied )

Mokbel associate #3: 11 years' jail for drug trafficking

Arrested in April 2006, this Mokbel associate was sentenced to 11 years' jail, with a non-parole period of nine years, for trafficking large quantities of methamphetamine.

The man worked closely with the snitch and was given the task of finding a place to run a drug lab.

In a conversation with Ms Gobbo, the snitch would later call his associate an idiot for picking a house next to Strathmore Primary School. It was vital information, allowing police to swoop on the premises.

Associate #3 used Ms Gobbo as his lawyer, advice he followed after the raids.

The criminal has since written to the Independent Broad-based Anti-corruption Commission (IBAC) stating he knows the lawyer was working for police and calling the lengths police had gone to to secure convictions "shady, dishonest and corrupt".

The DPP believes the man's conviction is tainted as, had he known why the snitch had turned against him, he could have had that evidence excluded from his trial.

Rob Karam has appealed his 35-year prison sentence, claiming he was deprived of a fair trial. ( Supplied )

Rob Karam, Pasquale Barbaro, John Higgs: Jailed for 'tomato tin case'

Convicted drug trafficker John Higgs is expected to appeal his jail sentence. ( Supplied )

Rob Karam, a close associate of Tony Mokbel, is serving a 35-year sentence for high-level drug trafficking and is likely to remain in jail until he's 70.

Karam was charged alongside Calabrian mafia boss Pasquale Barbaro over the seizure of Australia's largest ecstasy haul — 15 million pills hidden in 3,000 tomato tins.

However, in the wake of the Informer 3838 scandal, Karam has already lodged an appeal against his convictions.

Ms Gobbo bragged, in a letter to police, that she helped put Karam away, along with his co-accused Barbaro and John Higgs, whose appeals are imminent.

She also spoke of her fears about "a Calabrian mafia family" knowing it was a police informer who tipped them off about the ecstasy shipment, worth $440 million.

Karam's grounds for appeal are simple — his lawyer put her own interests ahead of his, depriving him of a fair trial.