The recent declarations of some European leaders demonstrated a new political impetus towards the Europeanisation of energy policy. Nevertheless, the complex allocation of regulatory competences between the EU and its Member States works against coordination and harmonisation. A possible solution could entail some Member States to promote ad hoc common policies through Schengen-like agreements, i.e., binding international law agreements outside the EU legal framework and thus escaping its formal and procedural requirements. Schengen-like agreements must however comply with the principle of supremacy of Union Law in order to be legally feasible. The compliance with the supremacy principle can be assessed on the grounds of three operational criteria: pre-emption, primacy of EU law and subsidiarity. The legal feasibility assessment conducted in the two areas of nuclear policy and security of gas supply shows that in the former area several of the most important licensing issues could be fruitfully integrated in a Schengen-like agreement.