Constitutional Justice in Times of Crisis: Lessons from Ukraine and Brazil on the Defense of the Rule of Law, Human Rights, and the Balance of Powers

The 21st century has forcefully refuted notions of a placid "end of history," presenting liberal democratic orders with a renewed wave of significant challenges. These threats manifest in diverse forms, from overt external military aggression to the subtler, internal erosion of democratic institutions. Within this turbulent context, the role of constitutional justice emerges as a critical area of inquiry for understanding the mechanisms that preserve – or fail to preserve – democratic societies during periods of profound crisis. This article examines the function, responsibilities, and divergent strategies of constitutional courts under such exigent circumstances, employing a comparative case study of Ukraine and Brazil. The analysis is grounded in a theoretical framework that juxtaposes Hans Kelsen's conception of a normative order protected by a "guardian of the constitution" with Carl Schmitt's theory of sovereignty defined by the "state of exception." This foundational tension is further explored through Karl Loewenstein's concept of "militant democracy" and an inversion of Bruce Ackerman's "constitutional moments," arguing that recent crises represent "de-constitutional moments" where judiciaries must actively defend the existing constitutional settlement against degradation. The article contrasts two distinct forms of democratic crisis and the corresponding judicial responses. The first case study analyzes the Constitutional Court of Ukraine (CCU) amidst a full-scale war of aggression – a quintessential Schmittian state of exception. The CCU’s response has been characterized by a militancy of perseverance; by continuing to operate, it has affirmed Ukraine’s constitutional sovereignty. Its key functions have included safeguarding non-derogable human rights under martial law and, crucially, upholding the constitutional prohibition on wartime elections. This adherence to legal text over political expediency has preserved the long-term integrity of the democratic process, demonstrating that constitutionalism provides a vital framework for state resilience even under extreme duress. The second case study examines the Brazilian Supreme Federal Court (STF) during a period of severe internal democratic backsliding, marked by populist attacks on institutions. The STF adopted an assertive, activist posture of constitutional defense. This militant jurisprudence is exemplified by its initiation of the "Fake News Inquiry" to counter organized threats against the judiciary, its robust defense of the electoral system against disinformation campaigns, and its forceful prosecution of the January 8th, 2023 anti-democratic insurrection. Furthermore, the STF acted decisively to restore transparency by declaring the opaque "secret budget" unconstitutional and protected vulnerable minorities by expanding rights for indigenous peoples and the LGBTQ+ community. Through a comparative analysis of these cases, the article concludes that while constitutional courts are indispensable bulwarks in times of crisis, the nature of the threat fundamentally shapes the judicial response. It identifies a central "dilemma of the militant jurist": to save the constitution, a court may feel compelled to stretch procedural powers, creating precedents that risk future abuse. The struggles of the CCU and the STF vividly illustrate that the rule of law is not a self-executing mandate but a project that requires perpetual defense, raising critical questions about the need to build broader institutional safeguards to support judicial courage and ensure constitutional resilience.