Supreme Court to rule on Charles' 'black spider' letters

The Supreme Court is set to rule whether letters written by the Prince of Wales to Government ministers should be made public.

The court has been asked to judge whether the Attorney General's office acted unlawfully when it prevented the publication of the letters in 2012.

The Guardian newspaper is seeking the disclosure of a series of letters between Charles and various government ministers between September 2004 and April 2005.

The case is believed to mark the first time that anyone has challenged the Attorney General's powers to block access to information.

Last year appeal judges unanimously ruled that the Attorney General has "no good reason" for using his ministerial veto and overriding the decision of an independent tribunal, chaired by a High Court judge, in favour of disclosure.

But, at the subsequent Supreme Court hearing, James Eadie QC, for the Attorney General, argued that the appeal judges "erred" in reaching their conclusion.

Mr Eadie told the justices that "the Government departments considered that they had no duty to disclose the requested information, and indeed had countervailing duties of confidentiality and as data controllers not to disclose it", and the Information Commissioner agreed.

The Attorney General had "strong grounds for his opinion that the Government and the Commissioner were right to find that the disputed information was exempt".