The Supreme Court have reached an "unconstitutional decision" by allowing letters written by the Prince of Wales to government ministers to be published, Tory MP Jacob Rees-Mogg has said.
The MP for North East Somerset said the ruling would make it very difficult for Prince Charles to do his job.
"It is the job of the Prince of Wales to interest himself in what his majesty's government is doing that's his role, that's his job", he said.
The Supreme Court ruling on the release of letters written by Prince Charles to government ministers "is a good day for transparency in government", Alan Rusbridger, Editor-in-Chief, Guardian News & Media has said.
In a statement, Rusbridger said: "We are delighted the Supreme Court has overwhelmingly backed the brilliant 10-year campaign by Guardian reporter Rob Evans to shine daylight on the letters Princes Charles has been writing to ministers.
"The government wasted hundreds of thousands of pounds trying to cover up these letters, admitting their publication would 'seriously damage' perceptions of the Prince's political neutrality. Now they must publish them so that the public can make their own judgment.
"This is a good day for transparency in government and shows how essential it is to have a fully independent judiciary and free press."
Prime Minister David Cameron has said the Government will now consider how to release the Prince of Wales's letters following the "disappointing" ruling by the Supreme Court.
Cameron said: "This is a disappointing judgment and we will now consider how to release these letters. This is about the principle that senior members of the Royal Family are able to express their views to government confidentially. I think most people would agree this is fair enough.
He added: "Our FOI laws specifically include the option of a governmental veto, which we exercised in this case for a reason. If the legislation does not make Parliament's intentions for the veto clear enough, then we will need to make it clearer."
Guardian Editor in chief Alan Rusbridger today praised reporter Rob Evans for his 10-year campaign to allow the letters to be published.
Evans originally made an application under the Freedom of Information act to see the Prince's 2004 and 2005 letters to Government ministers.
When he was refused, he went to an Freedom of Information Tribunal who ruled they could be published in 2012.
But the Attorney General made a ruling preventing the publication of the letters by the Guardian.
Reacting to the Supreme Court's decision on the letters, Clarence House said it was "disappointed the principle of privacy had not been upheld".
The Supreme Court has ruled a series of letters written by the Prince of Wales to government ministers can be published.
The decision overturns an earlier ruling made by the Attorney General, which was upheld by the High Court, preventing the publication of the so-called 'Black Spider' memos.
Supreme Court President Lord Neuberger said there was a "fundamental composite principle" behind the court's reasons for dismissing the appeal.
He announced: "That principle is that a decision of a judicial body should be final and binding and should not be capable of being overturned by a member of the executive."
A Freedom of Information Tribunal had ruled in 2012 that the letters, so named after the Prince's distinctive handwriting and abundant use of underlining and exclamation marks, could be published but the Attorney General had prevented the publication.
The Supreme Court is set to rule whether letters written by the Prince of Wales to Government ministers should be made public.Read the full story ›
Muhammad Ali welcomed the Prince of Wales and Duchess of Cornwall to his home city of Louisville, describing Charles as "the greatest".
The sport star's words came in a letter rather than in person as he was not well enough to join leading figures from the city at a cultural greeting for the royal couple, who were in the city on the final day of their US tour.
Instead, Louisville's Mayor Greg Fischer welcomed the royal couple by reading them Ali's letter:
(My wife) Lonnie and I welcome you to our hometown of Louisville, Kentucky, USA. We are honoured that you have come to explore, share and learn about new sustainable initiatives that are so close to your heart.
Louisville prides itself on being a compassionate city and we are confident that you will leave feeling a sense of our southern hospitality, caring for the environment, and yes - our love for college basketball.
As you travel back to your homeland, we hope you know how much this city respects and admires the many contributions you have made in the world.
We think you are the greatest.
The Duchess of Cornwall has paid a visit to the home of the world famous Kentucky Derby where she met two unlikely entrants.
As part of her trip to Lousiville, Camilla was at the Churchill Downs racecourse to celebrate the work of the Brooke, a worldwide equine welfare charity of which she is president.
Whilst there she met a pair of donkeys and gave them treats after "giving them a good scratch".
The visit came on the final day of Prince Charles and Camilla's four day trip to the US.
Prince Charles has said there is "awful lot to worry about" in relation to the world's environmental resources and wildlife.
He said his conservation efforts were driven by a need to leave future generations a world "which isn't even more destroyed and damaged and dysfunctional than it need be".
He listed his areas of concern from the continuing destruction of rainforests, to the threat to endangered animals like rhinos, elephants and tigers and the need for sustainable cities.
Charles said: "The world has looked to the United States for leadership in so many challenging circumstances in the past.
"However, today we are faced by truly exceptional challenges and threats - a veritable 'perfect storm' which, if not met by strong, decisive and far-sighted leadership, could overwhelm our capacity to rectify the damage and thereby destroy our grandchildren's future inheritance."
His comments came after he was presented with the exceptional leadership in conservation honour, from the International Conservation Caucus Foundation during a ceremony in Washington.