Source: European Parliament
Freedom of movement and residence for persons in the European Union is the cornerstone of EU citizenship, established by the Treaty of Maastricht in 1992. The gradual phasing-out of internal borders under the Schengen agreements was followed by the adoption of Directive 2004/38/EC on the right of EU citizens and their family members to move and reside freely within the EU. Notwithstanding the importance of this right, substantial implementation obstacles persist.