Abstract: The goal of this article is to raise the question of proliferation of modern understanding of the essence of social state in not only the area of social security, but also other areas, including criminal procedural law. Naturally, the subject of this research became the concepts of understanding of the essence of social state and the peculiarities of their application in the area of theory of criminal procedural law in examination of the question of the legal status of parties in criminal procedural relations overall and individuals with limited cognitive abilities in particular. The results of this research, reflected in its conclusions, consist in attention to the need for a change in understanding of the essence of a social state on the present stage of development of society and formation of its values on the international and national levels. The author proposes using the concept of “cognitive abilities” as a criterion for determining the level of realistic ability of a subject of violation to realize their rights and responsibilities, and as a result, attribution of individuals with limited cognitive abilities to the category of citizens requiring special protection by the state, which corresponds with the modern understanding of social state. This also justifies the novelty of the research, as well as designates the area of application of its results – in the theory of law in general, and in criminal procedural law particularly.