Criminal execution in prison and outside prison constitutes the core of the work. The argument is developed through an analysis and a comparison of the European systems. The study of rules approved by the United Nations and the European Union from the 1960s to the present shows that there is a first organic base to which related national laws and that you can finally assume an international penitentiary law. The work illustrates the legislation on prisons and examines the regulations of individual EU countries. Between differences and similarities, the author reflects on possible alternative measures to detention and compare the EU States with that of other countries, including China, Canada and South America.