The article analyses the functioning of the State language in the public authorities and local self-government bodies of Ukraine, pays attention to the ensuring by the Constitutional Court, the Supreme Court, local and appellate courts of the rights of a person who does not know the State language or speaks sign language, considers the implementation of functions by civil servants to ensure fundamental human rights and freedoms, and also examines the issue of observance of the fundamental language rights of national minorities in Ukraine, in particular in the territory of the Autonomous Republic of Crimea, for review. A comparative analysis of the functioning of state languages in European countries was also carried out. The author examines the use of the state language when submitting appeals, emphasising that from now on, the Law of Ukraine «On Administrative Procedure» is the legal act regulating the language of citizens’ appeals, according to which a person may submit the necessary documents for the proceedings in the state or another language, but in this case, the person is obliged to translate the appeal into Ukrainian. Cases of conflicts between the old and new legislation in the field of filing appeals are identified. The author analyses the regulatory and legal ways to ensure the implementation of functions in such public spheres as education, science, culture, sports, labour relations, television and radio broadcasting, print media, book publishing and distribution, advertising, healthcare, office work, and document management.
 The author focuses on the legal framework of the European Charter for Regional or Minority Languages in terms of protection of the rights of national and ethnic minorities. The author examines the issues of language policy in different countries, in particular in Spain, Switzerland and France, and in the context of protection of the rights of national and ethnic minorities, and concludes that the trend in most European countries is to try to balance the protection of minority rights and preserve linguistic diversity in the context of each country. The author emphasises that the State language plays a crucial role in the formation of the nation and the functioning of the State, primarily through its communicative, identification, ethnic and other functions.