A top aide to Queen Elizabeth II was involved in the downgrading of his security. This caused "significant tensions", according to the court.
The lawyer for Prince Harry challenged the decision and said that he didn't know Sir Edward Young, Queen's private secretary played a part in the decision.
Shaeed Fatima, QC stated that the decision was materially prejudiced because key information was withheld.
After he retired from royal duties in 2020, the duke was stripped of all protection.
Prince Harry does not believe it is safe to take his family to the UK without police protection. His lawyer previously stated that the UK "is and will always be his home".
His legal team claimed that the Executive Committee for the Protection of Royalty and Public Figures' decision regarding his security was invalid due to "procedural injustice".
They asked if it was appropriate for Sir Edward or any other members of Royal Household to sit on this committee. Prince Harry had previously been told that it was independent.
Ms Fatima, representing the duke, said that "He didn’t know at that point that the Royal Household had been involved at all."
She stated that Prince Harry should be able to directly make representations to Ravec in order to ensure that his arguments are properly communicated to committee members and given the opportunity to respond to any points made by other members, including the Royal Household.
Ms Fatima stated that Ravec did not receive his offer to pay for police protection and the decision was therefore materially prejudiced.
The court action is still in its early stages. Mr Justice Swift will be asked to determine whether Prince Harry is entitled to an arguable case. This decision will not be made for several weeks.
The Court Three oral and written submissions this morning were headline-making due to the details and, most importantly, the "significant tensions" between Prince Harry (Prince Harry) and Sir Edward Young (Queen's private secretary).
The court did not read any specifics, and sensitive information was not made public. It does however highlight the breakup in relations between the Sussexes, the Royal Household and their move abroad.
Whatever Mr Justice Swift decides there could be more legal action. Counsel for the Duke of Sussex indicated that he has started a second judicial appeal to determine whether he should be allowed fund the security rather than have taxpayers pay it.
Prince Harry's counsel said that an offer was made, which was also sent to Sir Edward Young 2020. However, it was not passed to Ravec.
The Home Office lawyers claim Ravec was allowed to make that decision - to provide protection for Prince Harry and Meghan in the UK on a case by case basis.
Sir James Eadie, QC representing the Home Office, stated in written arguments personal tensions between Prince Harry's and Royal Household officials were "irrelevant" for his status change when he retired from royal duties.
He stated that there was no basis to conclude that representations made by the duke to the committee would have resulted in a different outcome.
Prince Harry has previously stated that his private security team can't replicate the work done by the UK police, due to their access to intelligence and legal rights.
Since their California move, he and Meghan have rarely visited each other. The duke was photographed leaving a charity event in July 2021 when photographers followed him.
They also visited the UK in April to meet the Queen and attend the thanksgiving service at the Platinum Jubilee last year.
