The article is devoted to the investigation of the essence, role and correlation of two existing in Ukrainian legal science doctrines, namely, conceptions of legal state and supremacy of law, represented in constitutional and legal practice.

The analysis of the historical genesis, political and philosophical bases the essential features of legal state and supremacy of law, which resulted in the possibility to establish their distinctive and common features, ideals and goal.

Current process of integration of both doctrines in Western Europe has been traced in detail, which has accelerated right after the establishment of the European Union and the commencement of its corporate bodies, including the European Court of Human Rights.

The content common for features of both Legal Doctrines elaborated by a European legal science and recorded in the official documents of the European Commission «Democracy through the Law», namely legitimacy, legal certainty, the prohibition of arbitrariness, access to justice, human rights, non-discrimination and equality before the law is uncovered.

Common modern philosophical, ideological and political foundations of the two doctrines are justified as significant for national legal science findings, namely the philosophical ideals, the theory of constitutionalism, popular sovereignty and the social contract, the will of the people as a source of law, the doctrine of natural rights. Due to this kinship the concepts of legal state and the supremacy of law coincide in main features and in this part can be seen as identical.

However, the active use of the concept of the supremacy of law does not deny or prevent the use of the concept of legal state in the study of many political issues such as the legitimacy of the government, the relationship of democracy and the legal state, by the State in the context of protection of human rights and improvement of relevant constitutional and legal instruments, responsibility of the state for their actions, legal coherence of the state.