Financial constitutionalism as a vector for the transformation of the modern model of constitutionalism: from fiscal control to institutional sustainability

The modern model of constitutionalism is undergoing profound transformations under the influence of global economic and political-legal changes. One of the key challenges that accentuates the need to rethink theoretical and legal foundations is the growing crisis of fiscal sustainability, exacerbated by the consequences of globalization, digitalization, and climate changes. In these conditions, the concept of financial constitutionalism takes on special significance, representing not merely a form of budgetary regulation but a comprehensive institutional mechanism for ensuring the sustainability of public finances. The subject of this research is the legal foundations, institutional manifestations, and transformational trends of financial constitutionalism in the context of the evolution of the modern constitutional order. The analysis focuses on the relationship between financial sovereignty, public accountability, and legal limitations on power in conditions of layered and fragmented governance. The methodological basis of the research includes an interdisciplinary approach that combines doctrines of public law, theories of institutionalism, and economic-legal analysis. Comparative legal analysis methods, formal-legal methods, and a systemic approach have been applied to reveal the interconnection between fiscal and constitutional transformations. The use of historical-legal methods allowed tracing the evolution of fiscal control. The scientific novelty of the research lies in establishing financial constitutionalism as an independent and promising paradigm of modern constitutional governance, capable of serving as the core of institutional resilience in conditions of legal uncertainty. The study identifies the main principles and potential development vectors of financial constitutionalism in the legal systems of Global South countries and the post-Soviet space. The necessity of constitutional enshrinement of parameters for sustainable public finances as a tool for balancing economic rationality and social justice is justified. It is shown that the new paradigm requires a transformation of ideas about the role of the constitution as an instrument of macroeconomic governance. This framing of the problem goes beyond the traditional approach to financial law, which is limited to the instrumental role of the budget. Within the article, public finances are proposed to be viewed as a sphere possessing not only economic but also political-legal content, capable of directly influencing the structure, functioning, and legitimacy of state institutions.