Migration and Home Affairs

Alerts and data in SIS

Alert categories and requirements

SIS only contains alerts on persons or objects falling under one of the following alert categories:

  • Refusal of entry or stay: alerts covering third-country nationals who are not entitled to enter into or stay in the Schengen Area
  • Persons wanted for arrest: alerts for persons for whom a European Arrest Warrant or Extradition Request (Associated Countries) has been issued
  • Missing persons: to find missing persons, including children, and to place them under protection if lawful and necessary
  • Persons sought to assist with a judicial procedure: to find out the place of residence or domicile of persons sought to assist with criminal judicial procedures (for example witnesses)
  • Persons and objects for discreet or specific checks: to obtain information on persons or related objects for the purposes of prosecuting criminal offences and for the prevention of threats to public or national security
  • Objects for seizure or use as evidence in criminal procedures: this alert covers objects (for example vehicles, travel documents, credit cards, number plates and industrial equipment) being sought for the purposes of seizure or use as evidence in criminal proceedings

Types of data entered in SIS

A SIS alert always consists of three parts:

  1. a set of data for identifying the person or object, subject of the alert,
  2. a statement why the person or object is sought and
  3. an instruction on the action to be taken when the person or object has been found.

The quality, accuracy and completeness of the data elements enabling identification, are the key conditions for the success of SIS. For alerts on persons the minimum data set is name, year of birth, a reference to the decision giving rise to the alert and the action to be taken. When available, photographs and fingerprints must be added in order to facilitate identification and to avoid misidentification. The system also offers the possibility to add links between alerts (e.g.: between an alert on a person and a vehicle).

Biometric data

Furthermore, the use of biometric data (i.e. fingerprints) is gradually becoming a reality. Since 2013, SIS can store fingerprints which may be used to confirm the identity of a person (a one-to-one search) located by other means (alphanumeric search). However, the introduction of an AFIS (Automated Fingerprint Identification System) since March 2018 also allows identifying persons just on the basis of his or her fingerprints (a one-to-many search). Thanks to the AFIS, criminals and other persons of interest will find it even more difficult to enter and move within the EU using counterfeited, forged or other persons’ documents (imposters).

The functioning of SIS and its management

SIS consists of three major components:

  • a central system 
  • the national systems and
  • a communication infrastructure between the systems

An alert entered in SIS in one Member State is transferred in real time to the central system. It then becomes available in all the other Member States so that authorised users can search the alert on the basis of the entered data-elements.

Each Member State using SIS is responsible for setting up, operating and maintaining its national system and its national SIRENE Bureau. The EU Agency for large-scale IT systems (eu-LISA) is responsible for the operational management of the central system and the communication infrastructure. The European Commission is responsible for the general supervision and evaluation of the system and for the adoption of implementing measures where uniform conditions for implementation are needed, such as the rules for entering and searching data.