The given article is devoted to the problems of studying Legal English (further - LE) as the language for special purposes (further - LSP). The main idea of this work is to analyze general characteristic of competency-based approaches which are relevant in studying LSP used in lawyers' professional communication. These approaches are based on the theory both of LSP and Jurisprudence (in definite branch of Law) as well as the practical usage of LE in professional communication of lawyers' including the development of their skills and competencies. The competencies and their characteristics are considered to be of great importance in all types of professional communication and it should be thoroughly studied as the academic subject in the theory and practice of LSP. The scientific novelty of this research is that: the structure of a lawyer's professional / communication competency being realized when using LE is considered (theoretical and practical aspects); the interrelation of foreign-language communicative competence with professional competences of future lawyers is studied; problems and difficulties which lawyers meet in real practice of LE studying are analysed; the solutions of analyzed problems, educational tasks being of great importance for developing the abilities needed to master the professional foreign language competences are offered.