On June 14, 1985, in the Luxembourg town of Schengen, representatives of Belgium, Germany, France, Luxembourg, and the Netherlands agreed to eliminate border controls between their countries. Three of the EU member states--Denmark, the United Kingdom, and Greece--resisted this policy of eliminating their borders with other EU member states. As discussions of the implementation of the Schengen agreement continued, Italy signed it on November 27, 1990, and Spain and Portugal joined in on June 25, 1991. Full implementation of the Schengen Treaty began in July 1995 with the removal of border controls between six of seven Schengen states: Germany, the Netherlands, Belgium, Luxembourg, Spain, and Portugal. France continued temporary passport controls on some of its borders. Schengen's key measure is the removal of checks at common borders of EU member states while retaining controls at outer borders of EU member states where they meet nonmember neighboring states. Significant issues remain regarding the free movement of third-country nationals within EU territory. Challenges also remain in coordinating the customs and immigration regimes of the EU member states. The aim of the Schengen Treaty, therefore, is to establish unrestricted movement for citizens of EU member states within the territory bounded by the outer border of the European Union. 9 notes and 18 references