The spread of drugs is one of the biggest problems facing contemporary humanity. Their use has spread regardless of social class or financial status. Consumption that, at the same time as being related to the increase in fruitless problems such as crime and the proliferation of disease, is often accepted by society. In view of this, Brazilian managers, with the aim of providing the best treatment for the situation and the addict, based on an analysis of the world scenario, have started to look for public policies for this purpose, and consequently, to debate the criminal legislation surrounding the user. Thus, this book is dedicated to analysing the legal framework of the user, and tackles the debates about the (in)constitutionality of the criminal reprimand for the offence of drug possession. It takes an initial look at drugs, explaining everything from their beginnings to their legalisation in some countries. It presents arguments in favour of and against Law 11.343/06, as well as relevant aspects of its article 28, which deals with the typical nature of drug use. Finally, it testifies to relevant points in the votes of the STF ministers in Extraordinary Appeal 635.659.