It was a key court ruling on the "one country, two systems" principle that made Mr Justice Kemal Bokhary want to stay on as a permanent judge as he neared retirement.
One of the founding judges of the Court of Final Appeal, Bokhary describes this pivotal moment and many others from his years on the bench in his autobiography Recollections, seen exclusively by the South China Morning Post ahead of its release today.
It was the top court's majority decision in the so-called Congo case of 2011. The court ruled that, after the handover in 1997, a foreign state would have absolute immunity from Hong Kong courts. Bokhary's was the dissenting voice - he thought state immunity should be limited.
He writes that his dissenting views normally become accepted with time. But this case was a turning point as "what belongs to the 'two systems' part of the 'one country, two systems' principle is assigned by the court to the 'one country' part of the principle instead.
"It is difficult to see how the loss can ever be recovered."
However, after Bokhary gave a provisional judgment, and before Beijing replied to the court's request for an interpretation of the law, he was told his term as a permanent judge would not be extended when he reached the retirement age of 65 last October. He is now a non-permanent judge.
In the book, Bokhary reveals the thinking behind important decisions and reveals behind-the-scenes discussions with his peers. One of these is from a high-profile right-of-abode case in 2001, in which he tried to persuade his peers not to rule against mainland children adopted by Hongkongers.
He says he pleaded with the judges: "Are you sure you have to do this? Because if you do, there will be great sorrow in many households when the judgment is handed down."
And he writes that he was "deeply dismayed" to learn that a ruling in October 2011 prompted Cardinal Joseph Zen Ze-kiun to go on a three-day hunger strike. Zen was protesting against the judgment, which dismissed a challenge mounted by the Catholic Diocese over amendments to the Education Ordinance.
Bokhary also touches on human rights in the book, saying it is one area of the law that has changed "radically" during his years in the judiciary. "The fundamental change lies in the vastly increased preparedness of the courts to enforce them by effective judicial remedies. It brings what the law delivers into closer alignment with that to which the human spirit naturally inclines."
And he tackles Hongkongers' changing opinions on the law. Freedom of assembly is a case in point: "As for the general public, I think it true to say that it is becoming rather disenchanted with some demonstrations. And it is also true to say, I think, that many demonstrators have become less considerate of others than in the past.
"But for all that, the people have not forgotten - and will not forget - the causes and concerns which have united them and brought them out onto the streets in massive and peaceful demonstrations, not always without effect," he writes.
He doesn't shy away from one politically sensitive point - his refusal to attend the National Day flag-raising ceremony. "I ceased to attend because it dawned on me that the judiciary was not attending as a group. The chief justice sits in a different place from other judges," he writes. "And, as it seemed to me, the area allocated to the judges … was accorded not for the discharge of a duty but rather as a privilege."
It is not all serious reflection. Bokhary also recalls colourful, humorous anecdotes from both inside and outside the court, accompanied by his cartoons of crocodiles and other animals, some of them set in court, with the animals in judges' wigs.
In one incident, he tells how lawyer Patrick Fung SC was robbed, gagged and bound in a toilet in their legal chambers. Arming himself with a chair, Bokhary rushed to the rescue, only to find the robbers had fled.
Bokhary also recalls his upbringing, which wasn't as privileged as many may assume. Although he is the cousin of Ronald Arculli, chairman of Hong Kong Exchanges and Clearing, Bokhary recounts how he worked his way up from humble beginnings.
As a law student in London, he spent his summers working - as a porter in a department store, a packer in a basement sweatshop, and as a factory worker.
He writes that as a junior barrister with little money, he would bring in sandwiches made by his mother for lunch. But this embarrassed him, so he started skipping lunch and adjourning to the library instead, where he studied public international law.
"Life and the law has confronted Kemal Bokhary with some tough and disturbing realities, but his ultimate optimism and faith in the legal system is undiminished," said Klaus Pfeifer, managing director of Thomson Reuters, Legal North Asia, which owns Sweet & Maxwell, publishers of the autobiography.