The renegotiation deal in February includes the following:
"It is recognised that the United Kingdom, in the light of the specific situation it has under the Treaties, is not committed to further political integration into the European Union. The substance of this will be incorporated into the Treaties at the time of their next revision in accordance with the relevant provisions of the Treaties and the respective constitutional requirements of the Member States, so as to make it clear that the references to ever closer union do not apply to the United Kingdom”