In the article, the author examines the processes of changing legislation in Russia that reflect the general trends formed in society. The author concludes that by analyzing the trends in the development of domestic and foreign law, it is possible to predict the main directions of the development of legislation, including specific nature of the application of the principle of good faith.The paper notes that one of the trends that have developed in foreign legal systems is the constitutionalization of private law and the strengthening of the principles of socialization of law, expressed in the evolution of the principle of good faith. Dissemination of the principle of good faith in public legal relations forms another direction in law that, according to the author, means dissemination of the principle of good faith in public legal relations, which is why this principle is applied, in particular, in tax relations.As a result of the study, the author comes to the conclusion that in order to ensure uniformity of the constitutional law approach to the application of the principle of good faith, given that constitutional norms, principles and values should act as direct regulators of public relations within the process of socialization of law that is carried out simultaneously with the gradual blurring of the dividing line between private and public law, it is advisable to distribute civil law approaches to applying the principle of good faith as the most effective and developed, to other branches of law, which will correspond to the diversified nature of this principle.