Britain is committed under the Single European Act of 1986 to an "area without internal frontiers" within the European Community (EC). This commitment, however, is modified by a declaration allowing all EC member states to take such measures as they consider necessary to control immigration from third countries and to control international crime. The question has been raised as to whether Britain might implement a spot check system for EC nationals, giving the impression of more open frontiers while allowing immigration officers more time to examine documents in doubtful cases. Although there are no plans to introduce a compulsory identity card scheme, there may be merit in a voluntary system. At present, all West European countries except England, Ireland, and the Netherlands require citizens to carry identity cards. Police cooperation among EC members is important, an example being the assignment of British drug liaison officers in six EC embassies.