The author aims to conduct a detailed analysis of the grounds for considering administrative cases in the manner of simplified proceedings, identifying their features and problems of legal regulation. To achieve this aim, the author considers the changes in Chapter 33 of the RF Code of Administrative Proceedings by Federal Law No. 451 of 28 November 2018 and the clarifications contained in Resolution of the Plenum of the Supreme Court of the Russian Federation No. 42 of 17 December 2020; uses official statistics to track the effectiveness of the use of simplified proceedings; with the help of a rich empirical material, reveals judicial errors made during the transition to simplified proceedings for considering administrative cases. The methodological basis of the research is general and specific methods of scientific research (historical, comparative-legal, dialectical cognition, formal-logical, interpretation of law, and systems analysis). The author draws attention to the independence of the foundations of simplified proceedings from each other. Potentially, any category of administrative cases (with the exception of those listed in Part 2 of Art. 291), if one of the conditions specified in Paragraphs 1 and 2 of Part 1, Art. 291, and Part 7, Art. 150, may be subject to simplified proceedings. Consequently, the legislator has chosen the way to determine the possibility of considering administrative cases without being tied to the merits of the dispute. The author proposes to divide administrative cases into two groups: cases, in which the possibility of considering them according to the rules of Chapter 33 is due to (1) the expression of the will of persons interested in the outcome of the case (Paragraph 2 of Part 1, Art. 291; Part 5, Art. 216) and (2) the discretion of the court (Paragraphs 1, 3 of Part 1, Art. 291; Part 7, Art. 150; Part 1 of Art. 120). The author identifies a number of problems regarding the observance of the conditions for the transition to simplified proceedings for considering administrative cases. Thus, the law does not specify from what day it is necessary to calculate the 10-day period established by the court for the submission of objections by the administrative defendant; does not establish the form of expression of such objections. The disadvantages of the possibility (introduced in Art. 294.1 of the RF Code of Administrative Proceedings) of canceling the decision by the court that issued it in a case considered in a simplified proceeding are given. The problems of legal regulation identified in the course of the study may well serve as a vector for a further improvement of the mechanism for the court's consideration of the use of simplified proceedings for hearing administrative cases in order to comply with the procedural guarantees of the rights and interests of persons participating in the case that are established by law.