Anthony Dieni is accused of providing a drug user with a clean urine sample, giving false evidence on the user's behalf to a magistrate and stealing $164,000 from St Paul's Rehabilitation Prevention.

He is also accused of using his position at the Strathmore-based charity, to procure drugs from users and with providing his adult grandson with cocaine and cannabis.

A probe into his conduct by the Independent Broad-based Anti-corruption Commission (IBAC) has cast doubt over a series of judgments made in Victorian courts, because Mr Dieni advocated for 10 people with cases before the courts.

Mr Dieni was granted bail last week but couldn't be released from custody because his son, Frank Dieni, was unable to meet a $500,000 surety set in Melbourne Magistrates Court.

The matter returned to court on Monday, when Anthony Dieni's lawyers applied for the surety to be varied to $270,000.

Frank Dieni told the court he gave an incorrect value of his Melton West house last week, and confirmed he understood he risked losing his home if his father was released from custody and then fled overseas.

During his evidence, Frank Dieni confirmed he had been a member of outlaw motorcycle gangs, the Bros, the Finks and the Mongols, and in 2013 was fined $3000 by a magistrate on four counts of assaulting police, and using threatening and insulting language in a public place. He was spared convictions.

Frank Dieni also told the court he believed in using a "backhander" to discipline his children, when he said he would "enforce" a magistrate's order that Anthony Dieni not have anything to do with his grandson - Frank Dieni's son - if the older man got bail.

Asked by magistrate Ross Maxted how he would "enforce" the ruling, Frank Dieni replied: "I am old-fashioned and I believe that a backhander fixes things ... they [his children] do what they're told."

Mr Maxted asked Frank Dieni if he used a backhander on police, to which the former bikie said it was after police had pushed over his wife.

Frank Dieni has reportedly been an office-bearer with motorcycle clubs, but told the court he chose to leave the Mongols in 2014 and no longer had anything to do with any of his past clubs.

He said he was now on a pension whose weeks revolved around getting treatment for a back problem and caring for his infant son.

"I walked out [of the motorcycle gangs] for my own personal reasons," he said.

"I don't see them, I don't go to their premises, they don't come to my own."

The court heard Frank Dieni was in 2007 fined $1000 for keeping and supplying alcohol at an unlicensed venue. He also avoided convictions on those charges.

Prosecutors haven't opposed Anthony Dieni's bail application, but Mr Maxted said it was up to him to decide. He said he had to be satisfied a surety was of good character, to ensure an accused person got to court and abided by bail conditions.

"Character is a matter that is up to me ... surety is a very important person," the magistrate said.

Frank Dieni said he was his father's only option as surety as he had no other siblings and there was no one he could ask for help. Mr Maxted told him it was illegal to "crowd fund" a surety.

Anthony Dieni is charged with perverting the course of justice, perjury, trafficking a drug of dependence, theft and dealing in the proceeds of crime.

IBAC alleges Anthony Dieni arranged for the receptionist at the charity to provide a clean urine sample for a drug user Mr Dieni was helping, because the user had taken drugs and breached bail.

The receptionist hasn't been charged but IBAC's investigation is ongoing.

Mr Maxted said the charges Anthony Dieni faced went to the heart of the administration of justice in Victoria.

Mr Dieni appeared via video link on Monday.

He will remain in custody until Thursday, when his bail application continues.