Prime Minister Lee Hsien Loong will take the stand when his defamation trial against financial adviser and blogger Leong Sze Hian opens in the High Court next month.
The hearing, which is set to take place from Oct 6 to 9, was confirmed at a pre-trial conference with Justice Aedit Abdullah yesterday.
Responding to queries from The Straits Times, a spokesman for PM Lee said the Prime Minister will enter the witness box to give evidence and be cross-examined.
In a Facebook post following the conference, Mr Leong's lawyer Lim Tean wrote: "The expert witness who is to be called by PM Lee, Dr Tuan Quang Phan, will give evidence via video link from Hong Kong."
Dr Phan is an associate professor of marketing as well as innovation and information management at Hong Kong University Business School.
PM Lee will be represented by Senior Counsel Davinder Singh from Davinder Singh Chambers.
PM Lee had filed the suit over a post shared by Mr Leong on his Facebook page on Nov 7, 2018, which contained a link to an article by Malaysian news site The Coverage.
The article contained allegations that former Malaysian prime minister Najib Razak had signed "secret deals" with PM Lee in exchange for Singapore banks' help in laundering money from 1Malaysia Development Berhad, or 1MDB.
In papers filed in court, the legal team representing PM Lee said the allegations were "false and baseless", and it was clear Mr Leong had published the post "maliciously and to damage our client".
PM Lee is seeking aggravated damages and an injunction to prevent Mr Leong from publishing or disseminating the defamatory allegations, or other allegations of complicity in matters relating to Malaysia's embattled sovereign wealth fund.
In his defence, Mr Leong denied that he was being malicious.
He said in court papers that he took down his Facebook post on Nov 10 that year after being told to do so by the Infocomm Media Development Authority. He also argued that the article, on how Singapore and PM Lee had become targets of the investigation into 1MDB, was "a matter of public interest... whether or not it was correct".
Mr Leong filed a counterclaim against PM Lee, claiming that the defamation suit against him is an abuse of the process of the court.
In March last year, the High Court allowed an application by PM Lee to strike out the counterclaim.
The court said the abuse of court process is not recognised in Singapore law as a basis for one party to bring legal action against another.
The decision was upheld in September last year by the Court of Appeal, which noted that recognising the abuse of court process as a cause of action would "encourage unnecessary satellite litigation".
