On 14 June 1985, the Governments of the Kingdom of Belgium, the Federal Republic of Germany, the French Republic, the Grand Duchy of Luxembourg and the Kingdom of the Netherlands signed an agreement at Schengen, a small town in Luxembourg, with a view to enabling ‘(…) all nationals of the Member States to cross internal borders freely (…)’ and to enable the ‘free circulation of goods and services’.

The five founding countries signed the Convention implementing the Schengen Agreement9 on 19 June 1990, and were later joined by the Italian Republic on 27 November 1990, the Kingdom of Spain and the Portuguese Republic on 25 June 1991, the Hellenic Republic on 6 November 1992, the Republic of Austria on 28 April 1995 and by the Kingdom of Denmark, the Kingdom of Sweden and the Republic of Finland on 19 December 1996.

The Kingdom of Norway and the Republic of Iceland also concluded a Cooperation Agreement with the Member States on 19 December 1996 in order to join this Convention.

Subsequently, as of 26 March 1995, the Schengen acquis was fully applied in Belgium, Germany, France, Luxembourg, Netherlands, Spain and Portugal10. As of 31 of March 1998, in Austria and Italy11; as of 26 of March 2000 in Greece12 and finally, as of 25 March 2001, the Schengen acquis was applicable in full in Norway, Iceland, Sweden, Denmark and Finland13.

The United Kingdom (UK) and Ireland only take part in some of the provisions of the Schengen acquis, in accordance with Decision 2000/365/EC and Decision 2002/192/EC respectively.

In the case of the UK, the provisions in which the United Kingdom wished to take part (with exception of SIS) are applicable as of the 1 January 200514.

The Schengen acquis was incorporated into the legal framework of the European Union by means of protocols attached to the Treaty of Amsterdam15 in 1999. A Council Decision was adopted on 12 May 1999, determining the legal basis for each of the provisions or decisions, which constitute the Schengen acquis, in conformity with the relevant provisions of the Treaty establishing the European Community and the Treaty on European Union.

From 1 May 2004, the Schengen acquis as integrated into the framework of the European Union by the Protocol annexed to the Treaty on European Union and to the Treaty establishing the European Community (hereinafter referred to as the Schengen Protocol), and the acts building upon it or otherwise related to it are binding on the Czech Republic, the Republic of Estonia, the Republic of Cyprus, the Republic of Latvia, the Republic of Lithuania, the Republic of Hungary, the Republic of Malta, the Republic of Poland, the Republic of Slovenia and the Slovak Republic. As of 1 January 2007, this also applies to the Republic of Bulgaria and to Romania.

Some of the provisions of the Schengen acquis apply upon accession of new States to the EU. Other provisions shall only apply in these Member States pursuant to a Council decision to that effect. Finally, the Council takes a decision on the lifting of border checks, after verification that the necessary conditions for the application of all parts of the acquis concerned have been met in the Member State in question, in accordance with the applicable Schengen evaluation procedures and after consultation of the European Parliament.

In 2004, the Swiss Confederation signed an agreement with the European Union and the European Community concerning its association with the implementation, application and development of the Schengen acquis16, which shall be read in conjunction with Decision 2004/860/EC.

The SIS II, set up pursuant to the provisions of Regulation (EC) No 1987/2006 of the European Parliament and of the Council17 and Council Decision 2007/533/JHA18 (hereinafter jointly referred to as the SIS II legal instruments) constitutes a common information system allowing the competent authorities in the Member States to cooperate by exchanging information, and, is an essential tool for the application of the provisions of the Schengen acquis as integrated into the framework of the European Union. It replaces the first generation Schengen Information System that began operating in 1995 and was extended in 2005 and 2007.

Its purpose as laid down in Article 1 of the aforementioned legal Acts is ‘(…) to ensure a high level of security within an area of freedom, security and justice of the European Union including the maintenance of public security and public policy and the safeguarding of security in the territories of the Member States, and to apply the provisions of Title IV of Part Three of the (EC) Treaty (hereinafter referred to as EC Treaty) relating to the movement of persons in their territories, using information communicated via this system’.

In accordance with the aforementioned SIS II legal instruments, by means of an automated consultation procedure, the SIS II shall provide access to alerts on persons and objects to the following authorities:

1. (a)

   authorities responsible for border controls, in accordance with Regulation (EC) No 562/2006 of the European Parliament and the Council of 15 March 2006 establishing a Community Code on the rules governing the movement of persons across borders19;

2. (b)

   authorities carrying out and coordinating other police and customs checks within the country;

3. (c)

   national judicial authorities and their coordination authorities;

4. (d)

   authorities responsible for issuing visas, the central authorities responsible for examining visa applications, authorities responsible for issuing residence permits and for the administration of legislation on third-country nationals in the context of the application of the Community acquis relating to the movement of persons;

5. (e)

   authorities responsible for issuing vehicle registration certificates (in accordance with the Regulation (EC) No 1986/2006 of the European Parliament and of the Council20).

In accordance with the SIS II Decision, Europol and Eurojust also have access to certain categories of alerts. Both Europol and Eurojust may access data entered into SIS II in accordance with Articles 26 (alerts for arrest) and 38 (alerts for seizure or use as evidence). In addition, Europol may also access data entered in accordance with Article 36 (alerts for discreet or specific checks); and Eurojust may access data entered in accordance with Article 32 (alerts on missing persons) and Article 34 (alerts for a judicial procedure).

The SIS II is made up of the following components:

1. 1.

   a central system (the Central SIS II) composed of:

2. 2.

   a technical support function (CS-SIS) containing a database, the ‘SIS II database’;

3. 3.

   a uniform national interface (NI-SIS);

4. 4.

   a national system (N.SIS II) in each of the Member States, consisting of the national data systems which communicate with the Central SIS II. An N.SIS II may contain a data file (a national copy), containing a complete or partial copy of the SIS II database;

5. 5.

   a communication infrastructure between the CS-SIS and the NI-SIS (the Communication Infrastructure) that provides an encrypted virtual network dedicated to SIS II data and the exchange of data between SIRENE Bureaux as defined below.

The SIS II only contains the indispensable information (i.e. alert data) allowing the identification of a person or an object and the necessary action to be taken. In addition, according to the SIS II legal instruments, Member States shall exchange supplementary information related to the alert which is required for implementing certain provisions foreseen under the SIS II legal instruments, and for the SIS II to function properly, either on a bilateral or multilateral basis.

This structure built to deal with the exchange of supplementary information has been given the name ‘SIRENE’, which is an acronym of the definition of the structure in English: Supplementary Information REquest at the National Entries.

According to the SIS II legal instruments the supplementary information shall be exchanged in the following cases:

1. (a)

   in order to allow Member States to consult or inform each other whilst entering an alert (e.g. when entering alerts for arrest);

2. (b)

   following a hit in order to allow the appropriate action to be taken (e.g. matching an alert);

3. (c)

   when the required action cannot be taken (e.g. adding a flag);

4. (d)

   when dealing with the quality of SIS II data (e.g. when data has been unlawfully entered or is factually inaccurate);

5. (e)

   when dealing with the compatibility and priority of alerts (e.g. when checking for multiple alerts);

6. (f)

   when dealing with the exercise of the right of access.