Convicted Bali Nine drug courier Martin Stephens has filed an appeal to the Indonesian Supreme Court, claiming a disparity in the High Court decision that upheld the life sentence given by a lower court.

In a dossier lodged to Denpasar District Court, Stephens said the role he played in the failed heroin smuggling scheme was similar to the other five Australian drug mules who had their life sentences cut to 20 years in jail.

His appeal claims the decision showed there was a difference in treatment of similar cases in the Indonesian judicial system.

The life jail terms of Renae Lawrence, Michael Czugaj, Tan Duc Thanh Nguyen, Si Yi Chen and Matthew Norman were reduced to 20 years on appeal five weeks ago.

The High Court said the terms were cut because the five mules played only minor roles in the conspiracy to smuggle 8.3kg of heroin from Bali to Australia.

However, the life sentences of Stephens and Scott Rush were maintained.

Stephens was the only Bali Nine member to have his appeal rejected and his life sentence upheld. Rush did not appeal.

The five who had their sentences reduced had the same panel of judges, while another panel of judges handled the Stephens and Rush cases.

Comparing the decision and judge format in his and Rush's case to the other mules, Stephens said their roles in the failed venture were exactly the same as Czugaj and Lawrence.

Stephens, like Rush, Lawrence, and Czugaj, was arrested at Bali's Ngurah Rai airport on May 17 last year carrying blocks of heroin strapped to his body.

Bali Nine masterminds Andrew Chan and Myuran Sukumaran were sentenced to death, but no date has yet been set for their executions.

Lawrence, the only woman among the Bali Nine, has accepted the 20-year prison verdict, with no challenge from the prosecutor.

Her official acceptance of the sentence on May 30 made her the first of the Bali Nine to have an "einkracht" status, a Dutch term meaning the case is closed and the decision is solid.

Click Here for Bali 9 Case Information

BALI Nine drug mule Martin Stephens has a "lifer" cell mate whose eyes haunt Stephens' parents, Bill and Michele.

"This young man has only been in jail for five years and the light in his eyes is gradually fading as if the life is draining out of him," Mr Stephens said.

"Martin has to win this next and final appeal because it would kill us to look into his eyes in a few years' time and see nothing."

It is a chilling reminder of the importance of winning the most critical legal battle yet - to plead for mercy in the country's highest court to win their son, also a lifer, a reduced sentence.

So far Stephens has endured awaking to the sight of a cell mate dangling from the roof, intense homesickness and long bouts of daily confinement.

Click Here for Bali 9 Case Information