As from December 2007, the European Union plans to extend the abolition of checks at internal land and sea borders (and air borders by March 2008) to nine of the new Member States of the European Union (Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovenia, Slovakia and the Czech Republic).
People will be able to move freely, without checks, within an area expanded to 3 600 million km2  – the "Schengen area".
Up until this latest enlargement, thirteen EU Member States have been participating fully in the Schengen acquis (Germany, Austria, Belgium, Denmark, Spain, Finland, France, Greece, Italy, Luxembourg, the Netherlands, Portugal and Sweden) together with Norway and Iceland.  The United Kingdom has participated in only a part of the acquis (police and judicial cooperation).
With a view to this enlargement of the Schengen area, nine new Member States (Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovenia, Slovakia and the Czech Republic) have made a large number of changes to allow easier movement of persons: road, air and sea infrastructures have been adapted; new national networks have been successfully connected to the Schengen Information System; and standards to ensure the protection of people's data have been introduced.
The decision on extending the Schengen area has been taken following a detailed assessment, lasting two years, which the pairs of other Member States carried out on the new Member States' level of readiness.
Bulgaria, Cyprus, Romania and Switzerland are expected to play a full part in the Schengen acquis in the years to come.  Ireland will be able to participate in Schengen on the same terms as the United Kingdom whenever it wishes.