This article provides a comparative legal analysis of alternative (non-military) service in Greece, Switzerland, Finland, Estonia, Lithuania, Armenia, the Republic of Korea, and Taiwan in order to delineate the legal models and institutional mechanisms for implementing the right to refuse military service on grounds of conscience. It examines constitutional approaches to enshrining the duty of national defence and alternative service, and demonstrates the differences between systems that expressly recognise alternative service at the constitutional level and those in which the relevant guarantees are shaped primarily by legislation. The study analyses the institutional design of these systems (commission-based procedures for assessing convictions versus administratively centralised governance), as well as the types of alternative service, its duration, and the basic organisational elements (training, places of service, duration, etc.). It substantiates that the effectiveness of alternative service depends on normative clarity, the institutional capacity of the administering authority, and neutral criteria for assessing applicants’ convictions. The article formulates guidelines for improving Ukrainian regulation under martial law and in light of Ukraine’s European integration commitments.