The Mail on Sunday published excerpts from the Prince's diaries, and he claimed copyright infringement and breach of confidence. The case has been closely observed as a possible benchmark in the development of an ad hoc privacy law in the English courts.
Last December the Court of Appeal ruled in the Prince's favour, saying that the newspaper had clearly breached the prince's copyright and had committed a breach of confidence when it published parts of the diary.
The diaries were not completely private and excerpts of them were circulated to a few trusted friends of Prince Charles, but the court said that the publication in a national newspaper was a breach of confidence.
The newspaper had argued in court that it had a right to publish the diaries but gave up that pursuit in May of this year. It applied to the House of Lords asking the Law Lords to rule on the issue of privacy. It said this week that the Lords had failed in their "constitutional duty" to clear up the issue by refusing the case.
"A law of privacy is being developed by judges at a rapid pace without reference to parliament," said a Mail on Sunday statement. "It is most regrettable that the House of Lords has, for a second time, failed in its constitutional duty to examine whether this represents a threat to free speech."
Several high profile cases have taken place which, together, are seen as formulating an ad hoc right to privacy in England, which has never had such a right before.
Using the combined claims of the long-established breach of confidence law and the newer right to a private life contained in the European Convention on Human Rights, some have argued for an effective right to privacy.
The Lords also recently refused to hear an appeal against a ruling which banned publication of parts of a book about a singer's life. Loreena McKennitt won a High Court and Court of Appeal case barring publication of details of her life.
Her case argued that the publication would breach her rights to a private life, which are enshrined in the European Convention on Human Rights.
The Mail on Sunday has seven of the prince's diaries in its possession in total, and must now return them all.
