It’s been now over than 30 years since Piero Aimo wrote his book (Bicameralismo e regioni,1977) and in light of the stimuli given by the current debate on the Senate Reformation, which in Italy should be like a Chamber of autonomy, this contribution is aimed to re- examine and piece the institutional and political facts that have brought in 1946-47 the Italian republic forefathers to chose the bi- cameral structure of the Parliament, in search for the perfect two- chamber system. An unknown model to the concurrent constitution- al jurisdiction, at that time, based not only on the equal recognition of the two chambers of the Parliament, having the same popular le- gitimization and equal legislative power in the inspection and control procedures and also in trustee procedures, but also on the system of trust as set by the article 94 of Italian Constitution.