John Phillip Harrington, 63, pleaded guilty to attempting to possess and trafficking a marketable amount of cocaine the day his ACT Supreme Court trial was set to begin in March 2014.

He was serving a four-and-a-half year jail sentence and would have been eligible for parole next month.

But federal prosecutors last year challenged his sentence in the ACT Court of Appeal on grounds it was manifestly inadequate.

Harrington was arrested in after police caught him with more than 258 grams of cocaine - worth about $114,000 - following a trip to the United States in July 2011.

The drug was intercepted by Customs before police substituted it for an inert substance and followed the trail to Harrington.

A raid of Harrington's Griffith home uncovered 24 grams of cocaine and other drug paraphernalia, including scales and zip-lock bags.

Harrington claimed he had only been a small stakeholder in the criminal enterprise and intended to use his 15 per cent to fuel his $1200-a-day drug habit.

That claim was rejected by Justice John Burns, who said the offender had taken too many risks to be such a low-level player.

Harrington was sentenced to four years and six months behind bars, with a non-parole period of two years and three months.

In appealing that sentence, the Crown argued the judge failed to partially accumulate the sentences for the two offences, which were to be served concurrently, saying they involved separate and distinct criminality.

They also said there was no evidence to back up the 10 per cent discount to his sentence that Harrington received for pleading guilty the day of his trial.

In a decision handed down on Friday, Justice Richard Refshauge overturned the original sentence and found it was manifestly inadequate.

He agreed that making the sentences for the two offences wholly concurrent didn't reflect the overall criminality involved and said there had been no effective punishment for the trafficking offence.

"These offences were, in the sense we have described them, distinct acts of criminality," he said.

"They do not overlap in any factual or legal sense."

Justice Refshauge said Harrington played a principal role in the drug operation, and that his attempts to possess cocaine were not and "uncharacteristic aberration".

"The respondent was addicted to cocaine and was prepared to bring cocaine into the country illegally for his own use and to profit by further trafficking."

The court also found Harrington's guilty plea just before his trial began should not attract a discount to his sentence.

Justice Refshauge re-sentenced Harrington to eight years behind bars, with a non-parole period of four years and six months.

He will be eligible for release in August 2018.