Imprisoned for two decades in 2009 for his involvement in the slaying of career criminal Victor Pierce, Orman is appealing his sentence because super-snitch 'Lawyer X' Nicola Gobbo was part of his prosecution.

The 37-year-old wants to be freed on bail while awaiting his appeal, granted after a petition for mercy was accepted by Victoria's attorney-general last month.

Court of Appeal President Chris Maxwell on Wednesday said Orman's written case appeared to have "substantiation" through documents provided by police earlier this year.

If even a proportion of the assertions Orman makes are uncontested by police and prosecutors "it raises very serious questions", he said.

The prosecution case against Orman relied heavily on the evidence of another crook also represented by Ms Gobbo, Orman's sometimes-lawyer.

A royal commission is investigating the use of Ms Gobbo as a police informer, including against her own clients.

Orman watched Thursday's proceedings by video link from prison.

Director of Public Prosecutions Kerri Judd QC admitted there were some matters Orman raised that are "cause for concern" but added others appear "completely wrong".

Orman's legal team is still seeking more documents to back up his appeal and bail application.

But Justice Maxwell suggested if the current documents are enough to make out the more serious allegations, the case could proceed.

He said this would be a test case for others connected to Ms Gobbo, giving appeal justices the first opportunity to consider "how much conflict is enough" to overturn a conviction.

He pointed to a Queensland case where a conviction was overturned because a previous relationship between the prosecutor and defence lawyer was determined to be a big enough conflict.

Orman's lawyer Paul Smallwood wants to push on with a bail application, telling the court Orman has been behind bars for 12 years already - including two years awaiting trial.

Former underworld investigator Mark Hatt told the royal commission it's likely Orman would never have been convicted without Ms Gobbo's evidence.

He said there was significant corroborating evidence, including phone calls, used against Orman, but the calls alone were "probably not" enough to secure a conviction.

Four others including drug kingpin Tony Mokbel are also seeking to appeal their sentences because of Ms Gobbo's involvement in their cases.

Orman's matter is due back in court on August 2, when it's hoped a date for his bail application will be set.

Australian Associated Press