Najib Abdul Razak will know today whether he can proceed with his court challenge over the government's alleged refusal to implement a supplementary royal order for the remainder of his six-year jail term to be served as house arrest.

The Kuala Lumpur High Court is set to deliver a decision over the former prime minister's application for leave to commence judicial review that relied on the existence of the alleged royal addendum accompanying a main order that discounted his jail term and fine.

Judge Amarjeet Singh will determine...