Based on the thesis that the boundaries of any branch of law are determined by a complex of social relations possessing internal unity (which fully applies to social security law), as well as the need to maintain clarity of sectoral boundaries, the authors analyze the extent to which new social risks can change them. Based on an analysis of the risk of social exclusion proposed in science, the conclusion is substantiated that this and other new risks correspond to the structure and dynamics substantiated in the concept of social risk; social relations aimed at protecting against risks are characteristic of the subject of social security law. This demonstrates the preservation of the independence and strengthening of the sectoral specificity of this branch of law.