The article is prompted by the need to study new trends in the law of treaties in view of the current disintegration processes in the international relations. The rise of the treaty-making activities in the second half of XX century and the unprecedented institutionalisation of the international relations leave way for States’ losing trust in the institutions they have put in motion. As a result, the theme of exiting international treaties becomes of great current interest.

The conclusion and denunciation of an international treaty are construed as two equally significant acts in the exercise of State sovereignty. However, these are not always symmetrically reflected in their underlying constitutional regimes. The purpose of the present study is to analyse in comparative perspective the constitutional models of conclusion and denunciation of treaties and their development in time.

The study has been conducted by using the comparative and historical legal methods. A comparative overview of the constitutional models in the countries of Europe, the Eurasian Economic Union, BRICS, and some others including the USA reveals strengths and weaknesses in the constitutional frameworks governing the conclusion and denunciation of treaties.

The article demonstrates the existence of «asymmetric» national procedures that apply to the ratification of treaties on the one hand, and to their denunciation on the other, and possible legal consequences of the related constitutional model. Arguments are advanced in favour of the «symmetric» model, which allows the participation of national parliaments in both the ratification and denunciation of treaties. Special attention to be paid for the ways of coping with various legal consequences of the denunciation of treaties and the significance of this issue in the current circumstances have been highlighted. The need for systemic rethinking of the interaction between the denunciation of treaties and the development of the domestic legal order has also been emphasised.