The Attorney-General's Chambers (AGC) yesterday said it will put before the court Mr Li Shengwu's reply regarding his Facebook post which was flagged as being in contempt of court.
A spokesman said the AGC had received Mr Li's letter after the extended deadline of 5pm on Friday.
"The AGC notes that the document does not purport to comply with our letter of demand that Mr Li purge his contempt and apologise, but will nonetheless place the document before the court."
She added that the AGC is unable to comment further as the matter is now before the court.
The AGC's statement came after Mr Li posted his five-page reply on his Facebook page.
The post was the latest in an exchange between Mr Li, the eldest son of Mr Lee Hsien Yang and nephew of Prime Minister Lee Hsien Loong, and the AGC.
On Friday, the AGC said it had filed an application in the High Court to begin proceedings for contempt of court against Mr Li.
This involves a Facebook post Mr Li published on July 15 in which he wrote that the "Singapore government is very litigious and has a pliant court system", and said that foreign media had been cowed into self-censorship because of previous legal action.
He shared a link to a Wall Street Journal newspaper article that summarised the recent dispute between his father and aunt Lee Wei Ling on one side, and his uncle on the other, over their late father's home at 38, Oxley Road.
He also included a link to a 2010 New York Times editorial critical of his late grandfather, founding prime minister Lee Kuan Yew, and the Government over what it deemed as censorship of the foreign press.
The post was set to the "friends only" privacy setting, but it was published by several websites and widely circulated on social media.
The AGC said his remarks were an "egregious and baseless attack" on the judiciary. It asked that Mr Li delete the post, and sign and publish a written apology on his Facebook page by Aug 4.
In his post yesterday, Mr Li referred to the AGC statement on Friday, which included an exchange of letters with him, and shared the letter he sent.
In his letter to the AGC, Mr Li said the AGC had misunderstood his private post. He added that he had amended the post to remove any misunderstanding, but will not take it down.
Among other things, Mr Li said his criticism was directed not at the judiciary but at the Singapore Government's "aggressive use" of legal rules like defamation laws to constrain reporting by international media.
"I am not saying or imputing that the Singapore judiciary acts on the direction of the Singapore government, or that it is not independent, or that it will continue to rule in favour of the Singapore government in any proceedings regardless of the merits," he said.
He also said there is a difference in saying Singapore's court system is "pliant", as opposed to it being "compliant".
"A 'pliant' object is flexible, supple, or adaptable. This is in contrast to a 'compliant' object that is easily influenced or yielding."
He added that the court system encompasses the AGC, prosecutors and the general legal environment, before giving the analogy of how saying Singapore's medical system is inefficient does not mean its hospitals are incompetent or that its doctors are lazy.
Singapore's court system has much more flexibility to find the press liable for defamation compared with countries like the US, he said.
He also said the first sentence in his post makes clear it was focused on the Wall Street Journal's coverage of the Oxley dispute.
The second sentence, which was in parenthesis, stated: "(Keep in mind, of course, that the Singapore government is very litigious and has a pliant court system. This constrains what the international media can usually report.)"
"What I said in my private post in context does not pose any real risk of undermining public confidence in the administration of justice," Mr Li added.
He reiterated he would not have given approval for his private post to be shared publicly. He said he was thus not responsible for the "widespread and unauthorised publication and republication" of his post in Singapore, and suggested that the AGC should require mainstream media and other parties to remove their unauthorised publications of his post.
Separately, Mr Li, 32, told Reuters he expected to start an associate professor position with Harvard University - where he is currently a junior fellow - in autumn next year.
He said he would seek to defend himself through legal representation in Singapore, but would not be returning here. "I have no intention of going back to Singapore. I have a happy life and a fulfilling job in the US," he told Reuters.
Mr Li's July 15 post came shortly after a parliamentary debate on the allegations of abuse of power that his father and aunt levelled against PM Lee.