Chief Justice Sundaresh Menon yesterday upheld the appeal of a convicted drug trafficker, reducing her sentence from 11 years' imprisonment to eight.

In doing so, CJ Menon also laid out a new framework for sentencing offenders convicted of trafficking relatively small amounts of diamorphine.

Housewife and mother of three Vasentha Joseph, was arrested in November 2012 at a Jurong West carpark with more than 500g of a granular brown substance.

It was later found to contain 8.98g of diamorphine. The mandatory death penalty is in place for anyone convicted of trafficking more than 15g of the substance.

Vasentha had been found guilty of drug trafficking and sentenced to 11 years in prison.

But she appealed against the sentence because it was "manifestly excessive", said CJ Menon.

In 2012, Vasentha received a call on her husband's cellphone instructing her to take delivery of the drugs. She went on to sell these drugs to six men, according to court documents. Her husband was in prison at the time.

Allowing the appeal, the CJ said: "I am satisfied that, in the circumstances of the present case, the sentence... was manifestly excessive."

In calibrating the sentence, the CJ laid out a new framework judges could use as a reference. It uses the quantity of diamorphine trafficked as a starting point, as it "reflects the degree of harm to the society and is a reliable indicator of the seriousness of the offence".

For instance, those who traffic less than 3g of diamorphine should face between five to six years in jail and five to six strokes of the cane.

The recommended punishments scale upwards depending on the quantity of drug trafficked.

Judges should make adjustments to the recommended sentence based on "the offender's culpability and the presence of relevant aggravating or mitigating factors".

In the present case, CJ Menon noted that Vasentha had cooperated with the authorities, an "indication of genuine remorse".

He also pointed out that her culpability in the crime was relatively low. She was a person of low intellect, who had been "exploited" to act as a drug peddler, and was not part of a syndicate.

"In that light, I am satisfied that the sentence of eight years' imprisonment is fair and just," said the CJ.