This publication is a project to bring together linguists and lawyers to attack the problem of the principal distinction of the legal and lay languages as well as their common properties that our cooperation will help to reveal and make operational for law. The RF legal community is known to act on the assumption that any native speaker of Russian is able to read and understand any Russian text, including legal documents. The occasional conflicts in the area do not change the situation. It is the linguists and “critical legal authors” (Turanin 2010; Levitan 2014; Bogatyrev 2015), who joined the research project aimed at specifying the language difficulties blocking non-lawyer users from comfortable reading and understanding legal texts, and also finding what causes them. For linguists, their primary aim of research is collecting real-life data about the ability of various societal groups to deal with legal language. Based on the established sociolinguistic methodology, the research design contains some new categories, relevant for the project. It plans a linguistic typology of legal texts and questionnaires for users aiming at obtaining the users' (subjective) evaluation of textual difficulties, as well as their answers to questions about the content of the texts (the objective data section). The processed questionnaire data will be a source of information about the real status of legal language competence among national language speakers. Legal authors put forward the problem of inadequate legal terminology as a number one difficulty factor: legal terms, composed of lay language units, do not possess the semantic precision either within a word, or at the semantic boundaries outside it, and the legally relevant referential meanings may be unclear. Another major source of difficulty are the construction defects of law provisions. The results of the project are to be made public soon.