The UK parliament is expected to pass a controversial bill today (24 January) that will make it necessary to hold referenda on any future EU treaty changes involving transfers of power to Brussels.
The 'referendum lock' is part of the Conservatives' campaign promise to repatriate powers to the UK after David Cameron won a general election in May.
The bill covers any major changes to the EU treaties and the use of so-called 'passerelle clauses' that move unanimous voting to qualified majority in the EU Council of Ministers.
The idea is for major changes involving the country's national sovereignty to require the approval of British citizens.
Andrew Duff MEP (ALDE), the bill's most vocal opponent, claims in a recent op-ed that enhanced cooperation will also lead to a referendum. Enhanced cooperation allows a limited number of countries to apply shared rules in specific areas.
The bill, presented to parliament in November, has seen considerable debate on how to interpret "any major treaty change" and whether this might trigger a flood of UK referenda.
Hardliners meanwhile objected to loopholes in the bill such as the EU's 'flexibility clause', which allows the bloc to "renew" or "extend" existing treaties via simple government approval.
Open Europe, a Eurosceptic think-tank, has published a policy brief demanding a "tightening" of the referendum lock and giving the UK parliament even more say in future decisions than the bill proposes.
Europhiles criticse bill
More Europhile politicians, on the other hand, have deplored the bill as "bad Tory policy".
Liberal Democrat MEP Andrew Duff spoke to EURACTIV this week. In a telephone interview , he said the bill would "significantly blunt the EU's constitutional development" and claimed it was "intended to do so".
Duff will be taking the European Parliament's constitutional affairs (AFCO) committee to London on 27 January to start a debate in Westminster on the possible impact of the bill on the UK's position in Europe.
The MEP wants to raise awareness in other EU member states of what he describes as the "gravity of this unfortunate development".
According to him, Britain would place itself in a "legally and politically very awkward position" and be seen as an "untrustworthy negotiation partner" if the bill goes ahead.
According to the EU treaties, ministers must have the authority to commit their state to agreements, which under such circumstances would no longer be possible, Duff argues.
He also expects other member states to swiftly produce a counter reaction to "the spread of the infection of nationalist populism".
Duff assumes other countries would seek to ensure "more flexible forms of treaty change" in the future. "If this bill becomes law no future EU treaty revision will be possible if the UK remains a full member state," he wrote in a December article.
Labour to vote against
The Labour Party will be voting against the bill on Monday, but Duff wrote that he was hoping for sharper criticism from Labour when it reaches the Lords. He expects the Lords to block it due their greater "maturity".
Glenis Wilmott, Labour leader in the European Parliament, believes this is a bill that "pleases no one and achieves little". "If anything, this bill will undermine the sovereignty of the British parliament," she told EURACTIV.
The Conservatives in the European Parliament were generally unwilling to comment ahead of the vote.
However, Syed Kamall, a London MEP, made the following statement: "The bill is an admirable attempt to restore citizens' faith in government and parliament, following the loss of trust provoked by the EU's Lisbon Treaty being imposed upon British citizens without a referendum."
"Any decisions to transfer significant powers from Westminster to Brussels should require the agreement of the British people rather than being left to a political elite."
Another Tory MEP, Timothy Kirkhope, deputy chairman of the European Conservatives and Reformists (ECR) group in the European Parliament, told EURACTIV:
"We have to remember the context of this bill. The British people were promised a referendum on the European Constitution, which was rejected by the French and Dutch in their own referenda. Then the Labour government of the time reneged on its pledge and pushed through the identical Lisbon Treaty without putting that text to the people," Kirkhope said.
"That significant betrayal from the Labour government must never be repeated and this bill sets out in statute the people's right to a referendum before significant transfers of competences can occur," he added.
The two Conservative MEPs in the European Parliament's AFCO committee are not planning to go on the London trip.