Citizens are allowed to travel freely, without passports, between European countries covered by the Schengen agreement.
The pact was originally signed in 1985 by France, Germany, Belgium, Luxembourg and the Netherlands. Other European Union countries — as well as non-EU nations Norway and Iceland — joined later.
Poland, Hungary, the Czech Republic, Slovakia, Slovenia, Estonia, Latvia, Lithuania and Malta joined the EU in 2004. However, these countries had to wait until Dec. 21, 2007, before signing on to the Schengen agreement in order to meet the mandated requirements for police and border guards.
Romania and Bulgaria, which became EU members this year, did not meet the security criteria and will not enter the pact until later in 2008 at the earliest.
Cyprus, which also joined the EU in 2004, has asked to delay its border opening until later in 2008. Switzerland, which has signed on to the pact but not yet implemented it, is expected to fully participate in the border-free zone by 2009.