Mark Lewis, who has represented many victims of phone hacking by the News of the World, confirmed that legal papers were filed at the High Court on Wednesday on behalf of blog author Richard Horton.
In 2009, The Times revealed that Horton was the author of the Orwell award-winning blog Nightjack, which revealed various details about the life of a serving police officer.
The Rupert Murdoch-owned paper at first denied that it had accessed the email, but later admitted a journalist had hacked the messages for the story.
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At the Leveson Inquiry into press standards, The Times editor James Harding apologised for the incident and confirmed that the reporter behind the story had left the paper for an 'unrelated incident'.
However, Harding denied that he had given the greenlight for the email account to be hacked, or been made aware of the situation.
Horton is claiming aggravated and exemplary damages from Times Newspapers over breach of confidence, deceit and misuse of private information.
The Times was able to name the Lancashire detective as the author of the blog in June 2009 after the High Court denied his request for anonymity.
However, the paper's then legal manager Alastair Brett admitted to Leveson that legal documents filed at the time did not give the "full story".
It had been claimed that the journalist, Patrick Foster, had worked out Horton's identity using "publicly-available materials, patience and simple deduction".
But it later emerged that he had been able to correctly guess security questions for the anonymous Hotmail account to access the messages.
At the Leveson inquiry, Harding said: "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."
News International declined to comment.
The case follows a revelation last week that Sky News had hacked into the email of the 'canoe man' John Darwin, who was found guilty of faking his own death to claim on insurance.
Sky News said that the hacking was justified in the public interest as it exposed the criminal behaviour of his wife, Anne. The broadcaster also hit out at the "double standards" of The Guardian, which had broke the story.