Conservative former Shadow Home Secretary David Davis and Labour backbencher Tom Watson are applying for a judicial review of the Act, which was rushed through Parliament in just three days with the backing of all three major party leaders.
Backed by civil rights group Liberty, they will ask for a declaration from the High Court in London that the Act is not compatible with Article 8 of the European Convention on Human Rights, which guarantees the right to a private life.
The MPs have written to the Home Office giving them seven days’ notice of their intention to seek judicial review next week. If successful, the case – which could be heard in the autumn or early next year – would not strike down the Act but would require the Government to take action to ensure it is compatible with human rights law.
Prime Minister David Cameron and Deputy Prime Minister Nick Clegg said that the accelerated passage of Drip through Parliament was necessary because of an emergency created by a ruling in April by the European Court of Justice, which they said would have the effect of denying police and security services access to phone and email data.
Announcing the plan to seek judicial review, Mr Davis said: “Last week was a constitutional scandal. A piece of fundamental legislation was put through without proper scrutiny – without any real scrutiny.
“We were told it was simply reinstating the policy, but that is disingenuous. It was reinstating a policy which had been struck down by European law, without doing anything to make right the flaws which led to it being struck down, and it was reinstating policy which had fallen into very serious disrepute.”