The relevance of this article is associated with the need to counter attempts to falsify the history of the Second World War and the desire of a number of foreign politicians to rehabilitate Nazism, to create ideal conditions for the next («digital») segregation of the world’s population using the latest information technologies. The article examines the main provisions of social Darwinism that allowed the Nazis to «justify the expediency» of mass killings of the mentally ill. The author provides us with the data on the forms of destruction of psychiatric patients in nazi Germany and in the occupied territories. The paper analyzes the views of German psychiatrists, criminologists, geneticists who provided official science and healthcare in Germany in the twenties and forties of the last century. The empirical basis for this study was the publications of Western European and Russian authors devoted to the current problems of German forensic psychiatry and criminology during the reign of National Socialism. As a result of the analysis, a number of conclusions are drawn, in particular, the position is substantiated that any segregation (including those carried out on the basis of the severity of mental pathology or taking into account the level of intellectual development of the subject, his «social rating», nationality, income level, etc.) leads to massive violations of human rights, discrimination. In addition, the functional unity of morality and law is broken, and the law itself is deprived of the most important moral properties, namely; freedom, equality, justice. The idea is justified that in the era of «post-truth» only an objective understanding of historical experience can help humanity avoid the tragic mistakes of the past, strengthen the positions of opponents of ultra-liberal, neoconservative, etc. ideas, defend the system of traditional values.