The article examines the problematic issues of distinguishing and equating the concepts of "official language" and "state language". It was established that such terms as "official" and "state" do not contain any synonymous connection, because they reflect different lexical meanings. However, after analyzing all the constitutional acts of the countries of the world, it was highlighted that the concept of "official language" and the concept of "state language" at the legislative level are reflected as identical. The article contains an analysis of European countries regarding the definition of "state" and "official" language. The article also raises the problem of violation of the rules of melodiousness of the Ukrainian language in normative legal acts. Thus, it was highlighted that appropriate knowledge of the standards of implementation of the domestic language system by law-making subjects increases the authority of national legislation, and also facilitates the process of interpreting legal norms by the grammatical method, therefore, the correct operation of language norms should be a priority for every lawyer.