Harry, King Charles' younger son, is trying to overturn a decision by the Home Office – the ministry responsible for policing – which decided in 2020 he would not automatically receive personal police security while in Britain.
"One must not forget the human dimension to this case: there is a person sitting behind me whose safety, whose security and whose life is at stake," his lawyer Shaheed Fatima told the court on Wednesday as Harry watched on.
She had said in court filings made public on Tuesday that al Qaeda had recently called for Harry to be murdered and that he and his wife Meghan had been involved in "a dangerous car pursuit with paparazzi in New York City" in 2023.
Prince Harry stepped back from his royal duties in 2020 and now lives in California with his American wife Meghan and their two children.
His challenge was rejected last year, with the High Court ruling the decision was lawful, but he was granted permission to appeal.
Harry, 40, regularly conferred with his legal team on the final day of the two-day hearing, at times shaking his head, as the government's lawyers argued that it was the right decision to adopt a "bespoke" approach to his security.
"The basis for the decision-making and the bespoke approach being adopted was that it had positive advantages from a security assessment point of view," James Eadie, representing the Home Office, said.
After part of Wednesday's hearing concerning specific security arrangements was heard in private, Fatima said the case was incredibly important to him.
"His presence here and throughout this appeal is a potent illustration, were one needed, of how much this appeal means to him and his family," she said.
While Harry had been told he was getting "a special bespoke process ... he knows and has experienced a process that is manifestly inferior in every respect", Fatima added.
