Dr Mahathir Mohamad has served two stints as prime minister for a total of 24 years, and many policies have been envisaged and implemented under his watch.

However, some of his decisions and their consequences proved controversial and have come under the scrutiny of royal commissions of inquiry (RCI).

These ad-hoc fact-finding missions are appointed by the Yang di-Pertuan Agong - usually with advice from the prime minister - under the Commissions of Enquiry Act 1950 and have broad powers to investigate matters within their terms of reference.

Last week, the government announced an RCI would be...