The Times sued over computer hacking
The Times newspaper is being sued by police blogger Richard Horton after the paper accessed his email account, lawyer Mark Lewis has said.
The paper revealed Mr Horton was the author of an award-winning anonymous blog entitled "NightJack" in 2009.
At first it denied it had accessed his emails, but later admitted a journalist hacked messages to prove the story.
The Times Editor, James Harding apologised for the incident at the Leveson Inquiry into press standards.
But he denied he had agreed the hacking or been made aware of it.
Mr Lewis, who has represented many clients in hacking cases against News International, confirmed that legal papers had been filed at the High Court on Wednesday.
Mr Horton is claiming aggravated and exemplary damages from Times Newspapers for breach of confidence, misuse of private information and deceit.
The Times, owned by News International, named the Lancashire detective as the author of the blog in June 2009 after the High Court refused to grant him anonymity.
The paper's then-legal manager Alastair Brett admitted at the Leveson Inquiry that legal documents filed as part of the case did not give the "full story".
One stated that the reporter, Patrick Foster, had established Mr Horton's identity using "publicly-available materials, patience and simple deduction".
Mr Brett said he was furious when he had learned what the reporter had done and told him to find a way of establishing the detective's identity in a publicly available way.
Mr Harding told the Leveson Inquiry: "As editor of the paper I'm responsible for what it does and what its journalists do.
"I sorely regret the intrusion into Richard Horton's email account by a journalist. I'm sure that Mr Horton and many other people expect better of the Times, and so do I. So on behalf of the paper, I apologise."
In his blog, Night Jack - An English Detective, Mr Horton chronicled his working life in an unnamed UK town with descriptions of local criminals and his struggle with police bureaucracy.
It won the Orwell Prize for blogging in 2009, but he has not written since his identity was exposed.
He was given a written warning by Lancashire Constabulary, which said parts of his public commentary "fell short of the standards of professional behaviour expected of its police officers".
News International declined to comment.