The July Movement of 2024 in Bangladesh is not only an upheaval of the political nature, but also a complete legal break that re-articulated the structure of constitutional power and institutional legitimacy. This article questioned the Movement as a revolutionary process in which legality, legitimacy, and popular sovereignty came to compete with each other in a manner that undermined authoritarian power bases. By contextualizing the uprising in the issues of doctrinal contestations regarding revolutionary legality, the paper will be addressing Kelsen Grundnorm, Schmitt concept of constituent power, Fuller procedural morality, and Rawlsian aspects of public justification. With this prism, this paper examines the possibility of revolutionary legality to maintain long-term legitimacy beyond the short-term horizon of the regime overthrow. The analysis is conducted on two levels which are inter-linked, i.e. the doctrinal one and the policy-oriented one. The doctrinal aspect looks at the intellectual premises of constitutional break and succession, and the policy aspect looks at the institutional reform in the third republic in the judiciary, electoral administration and administrative accountability. Special emphasis is placed on the dangers of authoritarian entrenchment during transitional constitutionalism, frailty enforcement and how civil society, youth’s mobilisation and Diaspora activism change. Analogies with other South Asian and world revolutionary experiences would help in the critical evaluation of the experiences of Bangladesh. The paper posits that the July Movement cannot be successful unless the authoritarian order is toppled and legality established with essential qualities of transparency, participation and accountability in the processes. The article integrates theory and practice and thus makes a contribution to South Asian constitutional theory, and in offering an analytical framework to assess revolutionary constitutionalism in transitions states.