Assessing the efficiency of penitentiary system in Minas Gerais, Brazil: Evidence from Data Envelopment Analysis (DEA)

Brazil faces a persistent penitentiary crisis marked by institutional fragility, social inequality, and chronic underinvestment, while empirical evidence on the efficiency of its prisons remains limited. This study addresses this gap by evaluating the performance of 55 Penitentiary Units (PUs) in the Brazilian state of Minas Gerais using a dual-model framework based on Data Envelopment Analysis (DEA). Two dimensions of institutional performance are examined: Custodial Services Efficiency (CSE), which captures each PU’s ability to ensure secure accommodation, supervision, and administrative control; and Social Services Efficiency (SSE), which reflects the provision of staff-based services related to inmate well-being, including healthcare, education, and psychosocial support. These two dimensions are integrated into a composite index, the Prison System Efficiency Index (PSEI), which provides a global efficiency score for each PU. The findings reveal that nearly 90% of PUs operate with low or very low efficiency, and that small PUs tend to outperform larger ones. Paradoxically, PUs in less urbanized areas often show higher SSE scores despite custodial constraints. By revealing structural asymmetries and scale-related disadvantages, the results contribute to international debates on prison governance and demonstrate the need for more equitable and evidence-based penal policy in the Global South. • Proposes the Prison System Efficiency Index (PSEI) to assess efficiency. • DEA-based findings reveal urgent need for equity-driven prison reform. • 90% of prisons operate inefficiently in Brazil’s second most populous state. • Small prisons outperform large ones despite limited resources. • Penal efficiency is disconnected from rights, reintegration, and equity.