Unofficial immigration is difficult to define precisely as it depends on national legislation, which in turn differs from country to country and is often ambiguous. It has many different causes: the attractions of economic systems and labour markets; the institutional creation of illegality by regulatory systems that raise the necessary requirements for legal entry and for staying in the country; the lack of necessary resources if repressive policies are to be more effective; the “liberal obligation” requiring democratic states to respect human rights and welcome refugees; the action of humanitarian lobbies; the bypassing of the rules and the favouring of entries by the networks of relatives and fellow-countrymen. Despite all the rhetoric, this makes necessary manoeuvres of various kinds designed to bring out the hidden part of the immigrant population: 23 out of 27 countries in the European Union have adopted them in the last ten years and at least 5 million people have regularized their status.only subscribers can see the full article