Secession in the 20th-21st centuries have become subject to legal regulation at the level of current legislation issued on the basis of the provisions of the national Constitution. The paper analyzes three of the laws on secession. Two of them (the USSR and Canada) regulate the implementation of secession from the state, the third (China) prohibits secession. All the three acts are based on the interpretation of relevant constitutional norms. An analysis of these laws in terms of the purpose for their issuance, content, features, and the degree of achievement of the officially formulated goals shows a significant discrepancy between the officially set goals and the legal tools of legislative techniques used to achieve them. Despite the different names and officially stated goals for secession laws adoption, all the three laws are aimed at either preventing secession or significantly delaying the process. In the Soviet and Canadian laws that formally permit secession, the main role in the process of "delaying" the issue is assigned to the central authorities of the state, which are given broad powers and opportunities to recognize the results of a referendum held by the relevant region as invalid. Due to the nature of Taiwan’s status and its relationship with China the PRC law can hardly be seen as an attempt to create a legal mechanism of counteraction of secession. It is rather a political warning, made in the form of a legal act, of the inadmissibility, in the opinion of the PRC, the international legal formalization of the independence of Taiwan. The legislative regulation of secession issues does not yet contain new mechanisms that clearly ensure the democratic nature of state decision-making. However, no matter how weak the legislative regulation of secession issues is, it is a step forward in comparison with the use of force to solve regional problems.