This paper aims to assess the technical efficiency of Poland’s regional court system over a 20-year span in the twenty-first century by employing a constrained variant of Data Envelopment Analysis (DEA) applied to carefully processed time-series data. To estimate the technical efficiency of the system, various DEA models were utilised, beginning with the classical CCR DEA and super-efficiency DEA (SE DEA) approaches. However, significant shortcomings in the results produced by these methods were identified. To address these issues, a novel procedure involving constrained DEA was proposed, specifically designed to overcome these limitations and enhance the utility of DEA in evaluating judicial efficiency. Failure to account for the inherent limitations of classical or SE DEA models can lead to notable distortions in efficiency ratings assigned to individual Decision-Making Units (DMUs). Consequently, policy recommendations derived from such methods, intended to improve the actual performance of specific DMUs, may ultimately be unreliable or misleading.