European Union Bill

I just want to clarify the practicality of the hon. Gentleman's suggestion. He mentioned minimum judicial procedural rights as one of the home affairs subjects that relate to this. We opted in to that because it is important, for instance, for British citizens arrested abroad to be protected. Is he seriously suggesting that if that issue came up in future he would want it to trigger a referendum, even though it is within the existing competence that we have already conceded to the European level of government?