The moment of the start of an economic activity represents the critical junction, the key point, of the relationship between the State and a company and of the interaction between administrative powers of control and business autonomy. The regulation of this phase from the legislator and, during the implementation phase, its conditioning from the administrations significantly affect a plurality of interests, both individual and general. The ease to ‘do business’ and especially to start an economic activity is of relevant interest to the legal system as an element that affects the investment and the economic development of the country. From the point of view of the company, the regulation of the start of the economic activity, in so far as it is capable of conforming and influencing the future existence of the company, is decisive in shaping the extent of private autonomy in the pursuit of individual ends, first and foremost lucrative. Lastly, the configuration taken by the regulation of the access is also relevant for the companies already present on the market, which may receive direct or indirect protection from competition through public rules and which in any case have a qualified interest in the fact that only subjects that comply with legal requirements operate on that market. It is not by chance, therefore, that the phase of the access to the market is the privileged object of the public regulation of companies and that legal science has dedicated to it numerous and in-depth researches. But how is this regulation set up nowadays? How does the freedom of economic initiative act, as an individual subjective legal situation protected by the Italian and European economic constitution, towards the many public incoming constraints still in existence? How does the relationship between companies and public powers characterize and how did the recent economic and financial crisis affect this relationship? In order to answer these questions, the volume analyses, through the study of legislation and jurisprudence, public constraints on private economic initiative in certain sectors considered to be representative of the relationship between State and economy, such as the productive activities (industry, services and agriculture), the commercial distribution with specific reference to retail trade, pharmacies and fuel distributors and, lastly, the credit sector. The study puts legislation, which has been said to be central, together with the jurisprudence.