Former Ukip leader Malcolm Pearson has hit out at the government's refusal to address a further shift in power towards Brussels.
He told politics.co.uk the Conservative government was following a policy of "appeasement" in which Britain was bowing to "the malign project of European integration".
It followed an exchange in the House of Lords in which Lib Dem minister Tom McNally refused to address the issue until nearer its final deadline in May 2014.
Lord Pearson of Rannoch's concerns centre on provisions of the Lisbon treaty relating to policing and justice powers.
Britain can choose to opt out of the measures wholesale without requiring unanimity from the EU's 27 member states. It can then decide to opt back in on individual measures as the government sees fit.
"It's a fork in the road, this one," Lord Pearson told politics.co.uk.
"It's a very clear choice - between what the British people want and appeasement of Brussels by the political class."
On Tuesday he asked in the Lords: "Is the government not faced with a straight dilemma here - is it to be the wishes of the British people or is it to be appeasement?"
Lord McNally replied by telling peers "the government is very sensibly taking great care to study these matters".
The opposition spokesperson on the issue backed up the minister's stance, calling for a "sensible and practical approach".
"The Europhile propagandists often say 'oh well, it's already done'," Lord Pearson commented afterwards.
"To which I say, if someone has stolen a chunk of our sovereignty and we discovered it's been stolen, we want it back."
Ministers have promised a vote in both Houses of parliament on the issue when the government has decided on its stance.
But it remains unclear whether that vote will be whipped, or if the government will view votes as binding.
"The government is not resisting anything in Brussels. It's gone along with the financial supervision of the City of London and all our financial services, by an organisation which hasn't had its own accounts signed off by its internal auditors for 16 years," Lord Pearson added.
"This is an opportunity to get some of it back under the existing treaties without having to negotiate. That's why this one's so beautiful."
Last month Europe minister David Lidington announced a series of measures pledging to improve parliament's scrutiny of European Union business, which included the promise for a vote to take place.
He told MPs: "The government will conduct further consultations on the arrangements for this vote, in particular with the European scrutiny committees, and the Commons and Lords home affairs and justice select committees and a further announcement will be made in due course."