Solicitors for Mr Miranda, partner of Guardian journalist Glenn Greenwald, have written to the Home Secretary and Met Police commissioner for assurances that “there will be no inspection, copying, disclosure, transfer, distribution or interference, in any way, with our client’s data pending determination of our client’s claim”, law firm Bindmans LLP said.
Mr Miranda was detained at Heathrow Airport under Schedule 7 of the Terrorism Act 2000 as he changed planes on a journey from Berlin to his home in Brazil.
The announcement of his legal action comes as a Downing Street source denied any political involvement in the decision to detain him. A Downing Street source said Number 10 was “kept abreast of the operation” but denied any political involvement in the decision to detain Mr Miranda. “The Government does not direct police investigations,” they said.
The statement comes after Shadow Home Secretary Yvette Cooper called on the Home Secretary to say whether she or the Prime Minister was informed about the decision, after a White House spokesman said it was given a “heads up” on the move to detain Mr Miranda.
Mr Miranda’s firm of lawyers, said it is challenging the “legality of the action” under Schedule 7 of the Terrorism Act.
Criminal lawyer Kate Goold said: “We are most concerned about the unlawful way in which these powers were used and the chilling effect this will have on freedom of expression.”
The firm said that its solicitor Gwendolen Morgan, who is representing Mr Miranda, has written to the Home Secretary and the Met Commissioner calling for assurances that “there will be no inspection, copying, disclosure, transfer, distribution or interference, in any way, with our client’s data pending determination of our client’s claim.”
Mr Miranda was detained at Heathrow Airport under Schedule 7 of the Terrorism Act 2000 as he changed planes on a journey from Berlin to his home in Brazil. He claimed he was held for nine hours by agents who took his “computer, video game, mobile phone, my memory card – everything”.
Schedule 7 applies only at airports, ports and border areas, allowing officers to stop, search, question and detain individuals.
Its use has been criticised by Mr Greenwald – the reporter who interviewed American whistleblower Edward Snowden – as a “profound attack on press freedoms and the news-gathering process”.
A spokesman said the Guardian is “supportive” of Mr Miranda’s claim. Editor Alan Rusbridger told the BBC: “We will have to work out if that is legal or not, and that will be subject to legal challenge, I believe, by Glenn Greenwald and David Miranda because it’s not clear that he was actually committing any offence in carrying material through Heathrow.”
He went on: ““A lot of journalists the world over fly through Heathrow and I think some of them now are going to be quite anxious about how the British authorities regard this bit of Britain that is not quite Britain but is Britain.”
A Home Office spokesman said: “If the police believe that an individual is in possession of highly sensitive stolen information that would help terrorism, then they should act and the law provides them with a framework to do that.
“Those who oppose this sort of action need to think about what they are condoning. This is an ongoing police inquiry so we will not comment on the specifics.”
Last night Scotland Yard said the detention was subject to a “detailed decision-making process”, saying: “Our assessment is that the use of the power in this case was legally and procedurally sound.”
Police also said that he was allowed legal representation.
Shadow Home Secretary Ms Cooper said: “The Home Secretary needs to tell us whether she or the Prime Minister were informed or involved in this decision. Is it really possible that the American president was told what was happening but the British Prime Minister wasn’t?
“The Government need to explain who authorised the use of terrorism legislation in this case and what the justification was.”