Keywords: Crisis of Political Parties; Parteienstaat; Democracy's Transformation; State of Parties; Italian Constitution.
The paper studies the critical elements of the legal character and the complex functions of political parties in light of the legal provisions of Article 49 Italian Constitution and of the delays in the seventy years of constitutional fulfilment. These practices have led the Italian and European legal doctrine to understand the transformation of parliamentary democracy and the current crisis of the political parties by means of an analytical model of «State of parties» - "Parteienstaat", as defined by the German legal doctrine in the years '20 of the last century. This political-juridical evolutionary dynamic demands the carrying out of the constitutional provision on the «democratic method» in the political parties. Indeed, without the regulatory function of the political parties, there is the risk of transferring authoritarian drives to the State.