The relevance of the study of judicial reasoning in public law is related to the challenges of modern litigation, which require new approaches to the construction of a court decision. This is also due to the constitutional reform in Ukraine, in particular the latest amendments to the Constitution of Ukraine in the field of justice. The emergence of the priority issue of constitutionality led to the rupture of the system, where the protection of fundamental rights in a particular issue was essentially ensured in accordance with the case law of the European Court of Human Rights. The Constitutional Court of Ukraine always uses the decisions of the European Court of Human Rights to form its own legal positions, after which they actually become a substantive element of the motivating part of the decision of the Constitutional Court of Ukraine. It is concluded that regardless of whether the decision of the European Court of Human Rights has been ruled on Ukraine or not, it is a source of constitutional law of Ukraine.