ABSTRACT
EU justice and home affairs (JHA) law has attracted more forms of differentiated integration than any other area of EU law. There is a series of special rules applicable to associated non-member states: Norway, Iceland, Switzerland and Liechtenstein. These rules may be relevant when the time comes to develop a framework for the UK’s continued connection with EU law in this field after Brexit. In order to reconcile the overlap between the Schengen acquis and JHA cooperation among all member states, the Treaty of Amsterdam integrated the Schengen rules into the framework of the European Commission (EC) and EU Treaties. The treaties include general rules on ‘enhanced cooperation’, which in principle allow for the adoption of measures across most areas of EU law, including JHA law, without the full participation of all member states. There are also special rules on enhanced cooperation in several JHA areas linked to special decision-making rules: the ‘emergency brake’ and the ‘pseudo-veto’.
