Purpose. To analyze the evolution of the principle of the social state, various interpretations of the concept of the social state depending on the level of social responsibility of the state to the population, signs of the social state. Tasks. To analyze the interpretation of the Russian Federation as a social state. To reveal the content of the main features of the welfare state. Consider the principles-requirements of the welfare state. To reveal the features of modern trends in improving legislation and the mechanism of protection of social rights. To analyze the doctrine of the welfare state from the perspective of the concept of the «welfare state»; constitutional principles and norms defining the requirements of the welfare state and social human rights. Conclusions: The interpretation of the Russian Federation as a social state is analyzed in detail, an incomplete characteristic of the main features of the social state is revealed, an additional criterion based on the principle of social justice is proposed. The basic principles and requirements of the welfare state are substantiated. It is noted that the principles and requirements of the welfare state are expanded by the new Article 75.1 of the Constitution of the Russian Federation, where the interpretation of the welfare state is given through two main criteria: the creation by the state of conditions ensuring a decent life and free human development. As one of the main criteria of the welfare state, the legal norms regulating social human rights and the role of the state in finding a balance between a person's social activity and his ability to satisfy his social needs are noted. The conclusion is formulated about the existence of a wide range of social rights, and their security is noted as a key indicator of the implementation of the principle of the welfare state and the resulting principles-requirements. Modern trends in improving legislation and law enforcement are mainly aimed at increasing the effectiveness of the protection of social human rights in their violation, where the main role is assigned to the judiciary. The authors noted that to date, there are no unified views in the science of constitutional law on the admissibility, limits and conditions of judicial protection of social rights. First of all, the resolution of this situation depends on the place of social rights in the human rights system, the normative content of each specific right, their legal nature, as well as the scope of the powers of judicial bodies to invade the sphere of activity of legislative and executive bodies of state power. The concept, legal nature, normative content of the constitutional principle of the social state and social rights are investigated; examples from the practice of the Constitutional Court of the Russian Federation on the protection of social rights are given. Attention is drawn to the integration application of the principle of the social state in unity with other principles of law (free development, decent life, equality (equality), justice (social justice), legal certainty, proportionality (proportionality of restrictions on rights and freedoms), balance of public and private interests, etc.).