In this article the author explicates Herbert Hart's theory of an ascriptive language as it has been developed in his influential early paper "The Ascription of Responsibility and Rights". In the section 'Discussion' the author argues that the theory of ascriptive legal utterances, which is grounded on Austin's and Searle's theory of a speech act, provides the methodological basis for his analytical approach to philosophical and legal issues. In the section 'Results' the author justifies that an ascriptive is a specific speech (illocutionary) act. In the section 'Conclusion' the matter concerns the original linguistic formula of an ascriptive that accurately reflects its nature. This article elaborates on the interpretation of ascriptive speech acts in legal language by evaluating the influence of philosophy of language on the formation of modern legal philosophy, along with evaluating the contribution of conceptual development of legal philosophy in the speech acts theory.