sentences:  Enlargement of the Union is also contingent upon the consent of all existing members and the candidate's adoption of the existing body of EU law, known as the acquis communautaire.Until 2020, no member state had ever withdrawn or been suspended from the EU, though some dependent territories or semi-autonomous areas had previously left.The UK government invoked Article 50 of the Treaty on European Union on 29 March 2017 to formally initiate the Brexit process.