Articles 53 and 54 of the Constitution of the Republic of Lithuania establishes the principles of environmental protection. Initially, these constitutional norms were treated only as a goal of environmental protection, from which the subjective right to a healthy and clean environment does not derive. However, the practice of the Constitutional Court of the Republic of Lithuania, Lithuanian administrative courts and courts of general competence gradually broadened this approach. The accession of Lithuania to the European Union, the premise of which was the harmonization of national legislation with the legal norms of the European Union, as well as the ratification of the Aarhus Convention led to the fact, that the right to a healthy and clean environment was recognized as a constitutional right. Finally, this right can be defended in courts as a subjective right and as a public interest in environmental protection. The guarantee of the right to access to the courts in environmental matters enables the right to a healthy and clean environment to be protected.