The European Commission (EC) is the executive branch of the European Union, responsible for proposing legislation, implementing decisions, upholding the EU treaties and managing the day-to-day business of the EU. Commissioners swear an oath at the European Court of Justice in Luxembourg City, pledging to respect the treaties and to be completely independent in carrying out their duties during their mandate. The Commissioners are proposed by the Council of the European Union, on the basis of suggestions made by the national governments, and then appointed by the European Council after the approval of the European Parliament. It is common, although not a formal requirement, that the commissioners have previously held senior political positions, such as being a member of the European Parliament or a government minister.