SINGAPORE - The prosecution's intention to proceed with four drug importation charges against a man who had been acquitted of a charge involving identical facts amounted to an "abuse of the process of the court".

Chief Justice Sundaresh Menon said this on Friday (April 30) in written reasons for a majority decision by the Court of Appeal in March to reject a bid by prosecutors to proceed on four withdrawn charges against Malaysian Beh Chew Boo.

Mr Beh, who entered Singapore on a borrowed motorcycle on Oct 26, 2016, had faced five charges for different drugs found in a plastic bag in the motorbike's storage compartment.

He was tried on the first charge of importation of 499.97g of methamphetamine- also known as Ice - which carried the death penalty. After he was convicted, the other four charges were withdrawn.

In October last year, the apex court unanimously cleared him of the capital charge after accepting his defence that he was not aware of the Ice in the motorbike.

Mr Beh remained in prison despite escaping the gallows as prosecutors wanted to revive the four withdrawn charges and proceed with a second trial against him.

On March 2, in a 2-1 decision, Chief Justice Menon and Justice Steven Chong decided that the prosecution was not allowed to do so. Justice Tay Yong Kwang dissented.

On Friday, in written grounds for the majority decision, the chief justice said allowing the prosecution to reinstate and proceed with the withdrawn charges would amount to an abuse of process.

This was because it would "lead to the risk of manifestly inconsistent findings" between the apex court's decision to acquit Mr Beh and the findings in a subsequent trial of the four charges.

"In our judgment, this would have been an abusive collateral attack on this court's findings in the (prior judgment), and it would be unfair and unjust to Mr Beh or otherwise inconsistent with the fair administration of justice to permit the intended trial of the non-capital charges to be proceeded with," he said.

The majority noted that to prove the four charges, the prosecution intended to call the owner of the motorbike as a new witness and to cross-examine Mr Beh on certain text messages, which the lower court had disallowed during his trial on the capital charge.

The majority pointed out that it was the prosecution's choice not to call the witness and not to challenge the trial judge's ruling on the text messages before the apex court.

"Therefore, allowing the prosecution to proceed with a trial of the non-capital charges would be giving the prosecution a second chance in effect to 'undo' some of the consequences of the choices it had made," said the majority.

In his minority decision, Justice Tay said there was no abuse of process in the prosecution's decision to revive the four charges.

This was not a case where, upon acquittal, the prosecution decided to "proffer some more charges".

"Further, it is a time-honoured practice to proceed with capital charges first and to stand down non-capital ones," said Justice Tay.

He said the prosecution could not have raised arguments on the trial judge's rulings on the text messages as it did not appeal on the outcome of the trial.

Justice Tay added that the prosecution was seeking to establish the truth by calling the motorbike owner to testify.