The signatories to the Agreement signed at Schengen on 14 June 1985 – the five Member States Belgium, France, Germany, Luxembourg and the Netherlands – agreed that they would gradually remove their common border controls and introduce freedom of movement for all nationals of the signatory Member States, other Member States or third countries. The Schengen Convention was signed by the same five States on 19 June 1990 but did not enter into force until 1995. It lays down the arrangements and guarantees for implementing freedom of movement. The Agreement and the Convention, the rules adopted on that basis and the related agreements together form the ‘Schengen acquis’.
The objective was to remove border controls, approximate visa formalities and provide for cooperation of law enforcement agencies. There are common controls at the external borders of the Schengen area, but none at the internal frontiers, though document checks may still be carried out on individuals by competent police authorities.
Article 26 TFEU (inserted as Article 14 EC by the Single European Act 1986) provides that:
- The Union shall adopt measures with the aim of establishing or ensuring the functioning of the internal market, in accordance with the relevant provisions of the Treaties.
- The internal market shall comprise an area without internal frontiers in which the free movement of goods, persons, services and capital is ensured in accordance with the provisions of the Treaties.
As regards free movement of persons, the EU Member States had not earlier been able to agree on common provisions.
The 1985 Schengen Agreement, therefore, anticipated this provision on free movement and was an attempt by five Member States to achieve progress outside the EU framework. Italy, Portugal, Spain and Greece acceded to the Schengen Convention in 1990, Austria in 1995, Denmark, Sweden and Finland in 1996.The Czech Republic, Estonia, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia joined on 21 December 2007.
In April 2015, the Schengen area encompasses all EU Member States, except for Bulgaria, Croatia, Cyprus, Ireland, Romania and the United Kingdom. Bulgaria and Romania are currently in the process of joining the Schengen area. Non-EU states Iceland, Liechtenstein, Norway and Switzerland have joined the Schengen area.
A Protocol attached by the Treaty of Amsterdam to both the EU and EC Treaties (now TEU and TFEU) aimed to achieve the incorporation of the Schengen acquis, the 1985 Agreement, the implementing Convention of 1990 and decisions taken under those instruments, into EU law. The Protocol (now Protocol no.19) makes special provision for the UK and Ireland, which are not parties to the Agreement or Convention; thus, they are not bound by the Schengen acquis, but they are permitted to opt in to some or all of it. Denmark also has special arrangements.