Instead, Mitchell pleaded guilty to drug possession charges after police found 331.8 grams of methamphetamine, and 168.2 grams of cocaine inside a hire car he was driving.

Mitchell was arrested on September 24 last year when police found drugs and an extendable baton in his white Range Rover hire car. They also found digital scales with traces of cocaine on them in Mitchell's apartment.

Mitchell told police he knew what the drugs were, but not how much was in his car.

His defence lawyer, Peter Morrissey SC, told Judge Graeme Hicks that after Mitchell was released from custody on separate charges last year he had "drifted back into a criminal lifestyle ... dabbling in cocaine, drinking to excess and partying".

Mitchell was a popular and charismatic character, Mr Morrissey said, although "he's not particularly intellectually gifted". He later clarified this to say Mitchell was not "academically" gifted.

"When you say he's very popular, he's been shot twice," Mr Hicks observed.

Mr Morrissey told the court his client had never recovered from a shooting in October 2010, which left Mitchell in intensive care for a week and in hospital for a month.

Mitchell had lost 70 per cent of his liver, one kidney and his gallbladder in the attack, the court heard, and it had resulted in him becoming "a damaged person".

A forensic psychologist gave evidence that Mitchell suffered from post-traumatic stress disorder from the shootings, and Mr Morrissey said Mitchell's "severe PTSD" was linked to the criminal offending.

"He's got worse judgement than he'd otherwise have," Mr Morrissey said.

But, he conceded, "we don't submit it's a determinative feature" in Mitchell's criminal behaviours.

Mitchell's September arrest was part of an Australian Federal Police investigation into international drug trafficking. At the time, an AFP spokesman said the National Anti-Gang squad, the Australian Border Force, and Victoria Police's anti-gang Echo Taskforce were involved in the operation. The operation was heralded as smashing a hole through an international drugs ring, and netting $8 million worth of ecstasy.

Mitchell's high-profile arrest came as he was preparing to film a segment for commercial television on his life after quitting as the national sergeant-at-arms of the Bandidos in 2013 following a dispute with senior leadership about the direction of the outlaw motorcycle gang, Fairfax reported at the time.

In March, Mitchell pleaded guilty to possessing a trafficable quantity of drugs, and was told he faced a lengthy jail sentence.

But in the County Court on Friday, prosecutors significantly downgraded Mitchell's charges, with the former bikie enforcer facing only possession charges for the cocaine, which, the court heard, had a "pure weight" of 127.4 grams, and the methamphetamine, which had a "pure weight" of 259.4 grams.

Despite the downgraded charges, Mr Hicks said there was "no indication" the drugs found in Mitchell's car were for personal use.

The court was told the underworld figure was being kept in "oppressive" conditions in jail, and had been under 24-hour lock down in his cell until seven weeks ago, when authorities let him out for four hours a day.

Mr Morrissey told the court Mitchell should face no more jail time, and should be released on a community corrections order.

But Mr Hicks declined to sentence Mitchell on Friday, saying he would consider his decision and hand down a sentence in a week.