In general, constitutional law is not in favour of imperative mandate in most countries. In particular, a number of European Constitutions explicitly.
1) prohibit imperative mandate in a provision placed in the chapter on the national Parliament (Article 7, section III chapter 1 Titre III French Constitution 1791; among current constitutions, for instance: Article 67 of the Italian Constitution; Article 27 of the French Constitution; Article 38.1 of the German Basic Law; Article 67.2 of the Spanish Constitution; Article 68.2 of the Moldovan Constitution), and
2) proclaim that the Parliament represents the people (i.e. Article 147 of the Portuguese Constitution; Article 66.1 of the Spanish Constitution; Article 50 of the Andorran Constitution) and parliamentarians are representatives of the whole country and not of their constituency (Article 7, section III chapter 1 Titre III of the French Constitution 1791; Article 67 of the Italian Constitution; Article 152.2 of the Portuguese Constitution).
3)Some Constitutions also recognise, in the bill of rights, the fundamental right of citizens to accede to and exercise the public functions and positions. This happens in the context of the right of suffrage, or of participation in public affairs: Article 51 of the Italian Constitution; Article 23.2 of the Spanish Constitution; Article 25 of the Andorran Constitution, not to mention the French Declaration of Human and Civic Rights of 1789 (Article 6). The reach of such provisions will be developed below.