David Cameron is expected to pledge later on Wednesday that a Conservative government would set up a German-style constitutional court under a “sovereignty act”, designed to bulwark British law against undue influence from Brussels.
The UK would still be bound by rulings from the European Court of Justice. But Tory insiders said that Mr Cameron has been convinced by the precedent set by Germany that the ECJ was more reluctant to override a constitutional court than to rule in areas where no such domestic legal protections existed.
The proposed new legal bulwark is seen as particularly relevant to Britain because of the lack of a written constitution.
Mr Cameron is also said by party insiders to believe the proposed new act would give a Conservative government added bargaining power, in its bid to persuade the other 27 member states to allow the UK to repatriate social and employment laws.
The Conservative leader will set out his new European policy in a London speech at 4pm. The party this week confirmed it was abandoning its campaign for a referendum on the Lisbon treaty after the document was fully ratified.
The new policy received a positive reception at a meeting of Conservative MPs and peers addressed by Mr Cameron and William Hague, the shadow foreign secretary, on Wednesday afternoon.