The Government intends to opt out of a raft of EU police and justice measures, including the European Arrest Warrant, Home Secretary Theresa May has announced.
But Mrs May said that Britain is then likely to apply to opt back into some of the 130 cross-border agreements which the Government thinks are in the national interest.
The announcement was warmly welcomed by Conservative backbenchers, but Labour accused ministers of being mired in confusion over the issue, as Ms May was unable to identify which of the agreements Britain will seek to re-enter.
The issue splits the coalition down the middle, with many Conservatives keen to tear up the agreements, while Liberal Democrats insist that elements of the package must be retained. In a statement to the House of Commons, Mrs May made clear that no decision has yet been made within the coalition Government over which measures it wishes to hold onto.
Conservative minister Oliver Letwin and Lib Dem Danny Alexander are engaged in talks over exactly where the line should be drawn. A senior Lib Dem source said the party was "confident" agreement will be reached, adding: "We are approaching this by listening to the police and security services - the people tasked with keeping the British public safe - because they know how important a lot of these measures are to catching and prosecuting criminals both in Britain and abroad."
Shadow home secretary Yvette Cooper said the Government was adopting a "hokey-cokey" approach, unable to say whether it wanted to be out or in or out and then back in again.
And the leader of the UK Independence Party, Nigel Farage, described Ms May as "the modern-day Grand Old Duke of York". "She says she wants to opt out and then opt in again," said Mr Farage. "I suspect nothing of substance will actually be achieved."
Under the 2007 Lisbon Treaty, the Government must decide by May 2014 whether it wants to exercise the opt-out on justice and home affairs matters negotiated by the previous Labour government.
The terms of the Treaty mean that it cannot opt out of individual agreements, but must drop the package in its entirety and then apply to re-enter those elements which it wishes to retain.
Mrs May told MPs: "The Government is clear that we do not need to remain bound by all of the pre-Lisbon measures. Operational experience shows that some pre-Lisbon measures are useful, some less so and some are now entirely defunct."