The original sentence, handed down by the Northern Territory Chief Justice, was increased on appeal to nearly four years.

The Howard Government has used the case to argue that judges should be banned from taking Aboriginal customary law into account when making their decisions.

Stewart O'Connell, who has worked as an Aboriginal Legal Service lawyer for more than a decade, said the case was never about customary law, because the actions of the elder, known to the court as GJ, were never condoned by customary law.

"The reason I say customary law was never used as a defence is that a defence is something that provides a full acquittal to a charge," he told the ABC.

"He pleaded guilty to the charge, he didn't argue a defence. All that was put before the court was the customary context."

Mr O'Connell said the girl had been betrothed to GJ since she was about four.

"They were in fact considered married at that time so when she was four years old she was his wife already and considered to be his wife, much in the same way as we would consider husbands and wives in our culture," he said.

"So it was expected that when she became post-pubescent that she would then enter into an intimate relationship with him and she would bear children.

"She resisted that," he said. "She was brought up in a totally different era and in a totally different way."

Mr O'Connell said his client believed the girl had to be punished for having sex with another man and that she had no right to refuse him sex.

GJ and the community were confused by the revised prison term, the lawyer said.

He said customary law was not being used as a defence in many cases.

"It's just one aspect of mitigation that the courts should be taking it into account, much as they were taking into account the individual circumstances of any Australian citizen."