The subject of the article is an anti-executory opposition proceeding of article 840, Code of civil procedure (hereinafter c.c.p.). In the process of analyzing this institution, I will try to discuss its legal nature along with the purpose and functions as well as answer the question whether the institution meets the requirements imposed on it and thus constitutes a form of legally protected implementation of the law so as to enable the claimant to protect his or her rights. I will also try to put forward some of the postulates of de lege ferenda which, in my view, may improve the effectiveness and reliability of the court action in terms of adjudicating the proceeding. It is also essential to familiarize oneself with the issues raised by the institution, as the case itself is not a matter of an executory case, understood as a type of civil action related to the stage of civil proceedings. It is a nondependent action, the essence of which is to shape the law referred to the enforceable title following the legal basis of article 840 c.c.p. The characteristic of the opposition proceeding is the fact that it is at the junction of procedural and substantive law norms, and acts in the borderland with the validity in law.