This book explores, from an empirical perspective, the relation between crime and legal system: a relation that works both ways, where the evolution of crime phenomena modifies the legal system as well as the legal system changes criminal behaviour, through punishment and correction. This problem has been approached through the analysis of statistical data relating to some of the most relevant crime phenomena of the last decades: recividism, juvenile crime, immigration, cybercrime and hate crime. The social relevance of these cases is the starting point for a broader analysis of the social significance and function of the judicial system in the United States in the last decades.