The purpose of the book is to identify the legal effects of the renationalisation process on the EU and its Member States. The concept of renationalisation is expressed through MS's aim to verify the relationship with the EU. The thesis for the book is the return of renationalisation tendencies in the area of the Single Market, which is supported by, among others, an open criticism of the foundations of EU integration or considerations on withdrawal from the EU by some MS and the problems caused by migration and immigration. Part of the book involved an analysis of the internal market freedoms give a clear indication of the effects of the continuing trend of renationalisation on consumers, workers, entrepreneurs and MS. A definite influence on the above is the new, more dynamic, competition between Member States for leadership in sectorial EU policies (eg energy or agriculture), in certain areas (the euro) and the Union as a whole.