In his speech outlining his party’s new post Lisbon treaty policy on the EU, David Cameron pledged that no more powers would be transferred to the EU without a referendum:
Never again should it be possible for a British government to transfer power to the EU without the say of the British people.
If we win the next election, we will amend the European Communities Act 1972 to prohibit, by law, the transfer of power to the EU without a referendum.
And that will cover not just any future treaties like Lisbon, but any future attempt to take Britain into the euro.
He also pledged that any attempt to use the Lisbon Treaty’s “self amendment” clause would require approval by Parliament:
But people will rightly say that the Lisbon Treaty does not just transfer powers to Brussels today.
It allows further powers to be transferred in the future, because it contains a mechanism to abolish vetoes and transfer power without the need for a new Treaty.
We do not believe that any of these so-called ratchet clauses should be used to hand over more powers from Britain to the EU.
Furthermore, we would change the law so that any use of a ratchet clause by a future government would require full approval by Parliament.
Note that he is not pledging that power transfers arranged via the ratchet clause would require a referendum.
It would only require Parliamentary consent, and given that the government of the day normally commands a majority in the House of Commons and the House of Lords will tend not to oppose manifesto commitments and can be overridden by a determined government via use of the Parliament Act, this is not much of a brake. Indeed if this merely amounts to using a statutory instrument passed using the affirmative procedure (a single vote in favour in each house being all that’s required), it is practically no brake at all.
So it seems that use of the self amending clause of the Lisbon Treaty would enable some transfer of power without a referendum despite Cameron’s pledge in the earlier part of the speech, whilst using the ordinary revision procedure would.
However, the self-amending clause requires unanimity of the European Council, so a British government can veto any such attempts if it wishes to. If Cameron is serious when he says: “We do not believe that any of these so-called ratchet clauses should be used to hand over more powers from Britain to the EU.”, then his government (should the Tories be elected) should veto any and all such attempts.
Nevertheless the door is open for such a transfer of power to occur, without a referendum, should British government wish it. Indeed this is an encouragement to the EU institutions that some further increases in power can be achieved simply by using the ratchet clause, so long as they can get the British government onside. They don’t have to worry about getting the British people to endorse such changes in a referendum.