The application, to be heard by High Court judge Zaini Mazlan, will determine whether or not former 1MDB CEO Arul Kanda Kandasamy, a co-accused in the case, can be called as a prosecution witness.

Arul Kanda himself has not agreed to testify for the prosecution against his former boss.

Unlike Rizal Mansor and Tan Eng Boon, who were both discharged by the prosecution before testifying in cases brought against Rosmah Mansor and Tengku Adnan Mansor, respectively, Arul Kanda remains in the dock, accused of aiding and abetting Najib in the audit report tampering trial.

On May 20, the prosecution applied under Section 63 of the Malaysian Anti-Corruption Commission Act 2009 for Arul Kanda to testify against Najib.

That provision stipulates that whenever two or more persons are charged with an offence under the Act, the court may, on application by the public prosecutor, compel any of them to testify for the prosecution.

Gopal Sri Ram, lead prosecutor in the case, seeks to justify the application by contending that Arul Kanda has specific information that will materially affect the outcome of the prosecution’s case against Najib.

Najib’s lead counsel, Shafee Abdullah, has objected, citing prejudice to his client.

Section 63, which has its origins in India’s Criminal Procedure Code of 1898, was originally imported into Malaysian law via Section 19 of the Prevention of Corruption Act 1961.

Legal experts tell FMT the provision has only been invoked on two occasions in the past – both times in the early 1970s under the now repealed 1961 legislation.

In arriving at his decision, Zaini will have several important questions to grapple with, including whether an accused person can be called to testify for the prosecution, whether he can be compelled to give evidence against his co-accused and, critically, whether he can be compelled to do so at risk of incriminating himself.

One way or the other, the decision is bound to go down in the annals of modern legal history.