In the article, the author studies issues related to the execution of supranational regulatory powersand protection of national interests in the EU. The purpose of the article is to assess the EUlegislative process against the background of application of subsidiarity as a principle of protectionof national legislative powers in the areas of non-exclusive competence of the EU. The author hasused argumentative, empirical, logical and normative methods of research. At the same time, dueto the insufficient legislation and inadequate judicial enforcement of the subsidiarity principle, theauthor mainly relies on the argumentative research method in her conclusions. Thus, the authorjustifies the statement that the subsidiarity control mechanism established by the Lisbon Treatyhas not yet become an effective tool for national parliaments to play an important role in the EUlegislative process. The subsidiarity principle expected to be applied through this mechanism worksrather as a principle «for structuring the political discourse» on the EU legislative arena and does notreally limit the legislative power of the EU. However, the current weakness of national parliamentsin their dialogue with the EU Commission (as a main source of legislative initiatives at the Europeanlevel) may be successfully counterbalanced by cooperation between national parliaments andtheir national governments whose members make up the EU Council — a supranational institutionacting as a European legislator along with the European Parliament. The Monti II case demonstratedthat Council members, while remaining politically accountable to their national parliaments, couldsuccessfully function as a “transmission belt” between the EU Commission and national parliamentsin the subsidiarity control mechanism allowing parliaments to have a meaningful effect on theprocess of execution of EU legislative powers.