Adaptive constitutionalism: author's typology of models and criteria for sustainable legitimacy

Modern constitutionalism faces a fundamental challenge: how to maintain the stability of the constitutional order amid accelerating social, technological, and geopolitical transformations, avoiding both conservative ossification and destructive plasticity. In this context, the concept of "adaptive constitutionalism" acquires the status of a key analytical category that requires strict operationalization and systematization. Existing approaches are typically limited to describing institutional mechanisms or appealing to general principles of flexibility without constructing a comprehensive typology. In these conditions, arises the necessity for a theoretical toolkit capable of not only describing but also normatively evaluating the quality of adaptation processes. The subject of the study is the adaptive constitutionalism as a multidimensional and dynamic social institution, whose viability is determined by its capacity for internal evolution without the loss of its normative core. The aim of the article is to develop an original typology of models of adaptive constitutionalism and to formulate criteria for "sustainable legitimacy" as a normative ideal of a viable constitutional order. The methodological basis of this study consists of a systemic-typological approach, supplemented by comparative-legal and hermeneutical analysis. The scientific novelty of the work lies in the proposal of a multidimensional typology, including five models of adaptive constitutionalism – judicial-adaptive, formally-stable, hybrid-adaptive, evolutionary-pluralistic, and imitation-adaptive. For the first time in domestic and foreign doctrine, the concept of "sustainable legitimacy" is introduced and operationalized, synthesizing legal and socio-political legitimacy through five measurable criteria. The study demonstrates that adaptation models are not static but subject to dynamic transformation, including degradation – as observed in Hungary, Poland, and Turkey. The proposed typology possesses not only theoretical but also practical value: it can be used by legislators, constitutional courts, and international organizations to diagnose the resilience of constitutional systems. In conclusion, the necessity for further verification of the typology in a global context and its adaptation to digital challenges and non-colonial concepts of legitimacy is emphasized.