Answer given by Mr Frattini on behalf of the Commission
According to the Schengen acquis, which has been integrated into the framework of the European Union with the entry into force of the Treaty of Amsterdam, internal borders between Member States applying the Schengen acquis may be crossed without any checks on persons being carried out.
Authorities of the Member States are thus not allowed to carry out checks solely for the reason that the person is crossing the internal border.
This does not affect the right of airline companies to carry out identity checks within a commercial framework, i.e. when the passenger checks in, with a view to ensuring that he/she is the person indicated on the ticket or that he/she is entitled to certain discounts.
In addition, carriers are allowed to undertake checks for security reasons, for instance in order to ensure that the person boarding the plane corresponds to the person indicated on the ticket or where there are concerns that a person, whose conduct might disturb or jeopardise the safety of other passengers, boards an airplane. Such checks also apply to domestic flights.
These checks can be conducted through the verification of a passport or an identity card. Some carriers are organising pilot projects — according to our knowledge on a voluntary basis — with new technologies allowing the identification of a person.