THE chief justice of Indonesia's powerful Constitutional Court has hit out at the decision to grant Schapelle Corby clemency, saying drug crimes are worse than terrorism.

Corby's appeal for clemency was granted by Indonesian President Susilo Bambang Yudhoyono last week, who cut five years from the convicted drug smuggler's 20-year sentence.

The decision means Corby, who was busted in 2004 attempting to smuggle 4.1kg of marijuana into Bali in a bodyboard bag, is set to be released in 2017.

However, Constitutional Court Chief Justice Mahfud MD has called on Dr Yudhoyono to explain the clemency decision, joining a growing chorus of condemnation in Indonesia over the decision.

"Drug crime is worse than corruption and terrorism," he said.

"In corruption and terrorism cases, if the perpetrators are sanctioned to death, the case ends with their death. But drugs destroy life. It doesn't only kill the life of one person, but it destroys the life of the next generations."

He said it was normal to question the reasons behind the clemency as drug-related crimes were some of the worst and should carry heavy sentences.

Corby's sentence could end as early as 2015 if she is awarded the maximum eight months per year in remissions over the next two to three years.

The 34-year-old, known in Indonesia as the "Marijuana Queen", could be out of Bali's Kerobokan jail even sooner, and possibly as early as this year, if she is granted parole or approved for a prison program of "asimilasi", or assimilation, designed to allow well-behaved inmates to reintegrate with society.

Ika Yusanti, an official at the Justice and Human Rights Ministry, said Corby would be eligible for parole in September.

The head of Kerobokan, Gusti Ngurah Wiratna, will meet with Corby in person on Friday to officially inform her of the clemency decision and when she can expect to be released.

Originally published as Schapelle Corby 'worse than a terrorist' - judge