The meaning of the word "import" in the Misuse of Drugs Act is being mulled over by the highest court in Singapore, following a challenge by the prosecution against a decision by former Chief Justice Chan Sek Keong.

In a landmark judgment last year, then-CJ Chan had held that in order to make out an importation charge, prosecutors had to prove that the offender had brought the drugs into Singapore for the purpose of trafficking.

He had made the ruling in the case of Adnan Kadir, 41, who was sentenced to the mandatory minimum of five years' jail and five strokes of the cane for importing 0.01g of heroin. The maximum jail term for importation is 30 years.

But the prosecution disagreed with then-CJ Chan's interpretation of the law and brought the case to the Court of Appeal.

On Monday, Deputy Public Prosecutor Lee Lit Cheng argued that the meaning of "import" in the Act is unambiguous - to bring drugs into Singapore - and does not entail the element of trafficking.

But Adnan's lawyer, Mr Abraham Vergis, aligned himself with then-CJ Chan's characterisation of importation as essentially a trafficking offence with a cross-border dimention.

The Court of Appeal will give its decision at a later date.