Based on the analysis of regulatory documents, including both regulations and ethical codes, as well as foreign doctrine, the article deals with a range of issues related to the institution of separate opinions of the judges of highest courts, both national and supranational. First of all, in this regard a set of legal and ethical requirements, which restrict the expression of the autonomous position of a judge in the administration of constitutional justice, is studied. In particular, it focuses on such significant issues as the procedure for submission and publication of separate opinions, as well as the fundamental criterion of loyalty to the content and form of separate opinions.