Schengen Agreement, international convention initially approved by Belgium, France, West Germany (later Germany), Luxembourg, and the Netherlands in Schengen, Luxembourg, on June 14, 1985. The signatories agreed to begin reducing internal border controls, with the ultimate goal of allowing free movement of persons between countries within the Schengen area. To implement this, a system of shared policies regarding visa and asylum applications was adopted by member countries, and a massive database, known as the Schengen Information System (SIS), was created to share information about persons and goods transiting the Schengen zone.
By the time the agreement went into effect in March 1995, Italy, Spain, Portugal, and Greece had joined the original five members, with Austria, Denmark, Finland, Iceland, Norway, and Sweden following soon after. Although the Schengen Agreement originated outside the framework of the European Union, the Treaty of Amsterdam brought it into the corpus of EU law in 1999. Upgrades were made to the SIS to aid national law enforcement bodies. In 2007 the Schengen area expanded to include the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia. The area was further enlarged by the addition of Switzerland (2008), Liechtenstein (2011), and Croatia (2023).