There has been a clear tendency of judicial acts to appeal to the doctrine of estoppel, which is considered as a consequence or one of the manifestations of the principle of good faith. The authors of the article consider current judicial practice of using the estoppel rule regarding the rules of Russian procedural law, so-called “procedural estoppel”. The article analyses the most common cases when courts apply the estoppel rule; considers normative substantiation of the possibility of applying the doctrine in judicial acts. It raises the question of the appropriateness of introducing the term “estoppel” into jurisprudence in Russia, as it is appropriate in doctrine but people do not understand it in legislation and judicial practice, scholars say it should be avoided there. Besides, the procedural estoppel is still in the process of formation now. In the final part of the study, the authors consider the conditions necessary for the court to use the estoppel mechanism, in particular, which of the constituent elements really are actually established by the courts in the application of the procedural estoppel, which can only be presumed, presumed, and which are not considered necessary.