This book offers a pioneering examination of how the Brazilian legal system is evolving to protect vulnerable populations amid growing social inequalities and judicial transformation. It introduces the concept of the Procedural Microsystem for the Protection of the Vulnerable, a procedural micro-system recognized by Brazil's Superior Court of Justice (STJ), and explores its implications for constitutional and institutional realignment within the justice system.

Focusing on two key autonomous institutions, the Ministério Público (Public Prosecutor's Office) and the Defensoria Pública (Public Defender's Office), this book analyzes their roles in promoting access to justice and safeguarding fundamental rights. Through a detailed study of legal frameworks, jurisprudence, and institutional practices, it investigates how these bodies support structurally and socially vulnerable groups, including children, the elderly, women, racial minorities, people with disabilities, and Indigenous communities.

Combining theoretical insight with practical relevance, this book introduces innovative concepts such as procedural constitutionalization, functional complementarity, and decolonial due process of law. It also draws on comparative legal experiences, particularly from Latin America, to situate its analysis within broader debates on legal pluralism, inclusive development, and human rights.

Essential reading for legal scholars, judges, prosecutors, public defenders, and policymakers, this book is especially relevant for those researching procedural law, constitutional law, institutional performance, and the protection of vulnerable populations in the Global South.