1. Before entering an alert, the Member State shall check whether the person or the object concerned is already the subject of an alert in SIS. To check whether the person is already the subject of an alert, a check with dactyloscopic data shall also be carried out if such data are available.
2. Only one alert per person or per object per Member State shall be entered into SIS. Where necessary, new alerts may be entered on the same person or object by other Member States, in accordance with paragraph 3.
3. Where a person or an object is already the subject of an alert in SIS, a Member State wishing to enter a new alert shall check that there is no incompatibility between the alerts. If there is no incompatibility, the Member State may enter the new alert. If the alerts are incompatible, the SIRENE Bureaux of the Member States concerned shall consult each other by exchanging supplementary information in order to reach an agreement. Rules on the compatibility of alerts shall be laid down in the SIRENE Manual. Departures from the compatibility rules may be made after consultation between the Member States if essential national interests are at stake.
4. In the case of hits on multiple alerts on the same person or object, the executing Member State shall observe the priority rules for alerts laid down in the SIRENE Manual.
If a person is subject to multiple alerts entered by different Member States, alerts for arrest entered in accordance with Article 26 shall be executed as a priority, subject to Article 25.