In the landscape of the complex legal architecture of the European Union (EU), Ireland possesses some unique qualities in regard to its membership. This is largely in part due to the several Protocols to the European Treaties it negotiated over subsequent treaty changes since the country’s accession in 1973. In addition to its potentially more well-known Protocol relating to Article 40.3.3. of Bunreacht na hÉireann, which sought to protect Ireland’s then effective ban on abortion, Ireland has three Protocols which relate to the EU’s Area of Freedom, Security and Justice (AFSJ).

Protocol 21 attached to the Treaty on the Functioning of the EU (TFEU), which came into effect in its current form with the Lisbon Treaty on 1 December 2009, is the focus of this paper. Protocol 21, in the most basic terms, provides Ireland with right to opt-out and the choice to opt-in to legislation adopted to govern the AFSJ under Title V of Part 3 TFEU on a case-by-case basis. Protocol 21 is complemented by Protocol 19 and Protocol 20.

Protocol 21 has been an important part of Ireland’s membership of the EU since the Amsterdam Treaty came into force in 1999. This has become increasingly the case in the post-Lisbon context. The Protocol, together with Protocol 19 and Protocol 20, provide Ireland with flexibility in its approach to European integration in potentially politically sensitive areas and allows for a pragmatic approach to its engagement with the AFSJ. On the other hand, the Protocol has made Ireland’s relationship with the EU acquis more complex and fragmented.

This paper provides an overview of the AFSJ as well as the history, content, and operation of Protocol 21.