Metrological culture as an antidote to judicial errors

In today’s society, an increasing number of criminal proceedings are decided with reference to scientific knowledge used to reconstruct factual reality on the basis of experimental findings and measurements (so-called scientific evidence), whose results often carry decisive weight in final decisions.

The growing relevance of scientific evidence in the judicial context is accompanied by increasing trust, on the part of legal practitioners, in information obtained through scientific analytical methods. However, considering such evidence automatically more reliable because of its apparent objectivity compared to other forms of proof, such as witness testimony, is a potentially flawed approach. Science, too, has intrinsic limitations and does not ensure absolute certainty, as is sometimes assumed, particularly in judicial decision-making.

The PRIN 2022 Project: metrology enters criminal proceedings

To ensure a more informed evaluation and use of technical-scientific evidence, it is necessary to introduce into criminal proceedings the fundamental concepts of metrology, the discipline that forms the foundation of scientific investigation. This was the objective of the research project “Towards Greater Reliability of Technical-Scientific Evidence through Forensic Metrology. A New Antidote to Judicial Errors,” funded by the European Union – Next Generation EU under the PRIN 2022 call of the Italian Ministry of University and Research.

The project title clearly expresses its underlying hypothesis: metrological culture can provide valuable support in managing scientific evidence, particularly, but not only, in assessing the reliability of results obtained through forensic science techniques and methods, thereby helping to minimize the risk of “false positives,” that is, wrongful convictions.

Metrology is, by its very nature, the science that provides the conceptual tools to assess, manage, and interpret the uncertainty that characterizes every measurement. Not surprisingly, its crucial role in the forensic field has also been recognized in the PCAST Report (2016) of President Obama’s Council of Advisors on Science and Technology and in the 2022 Sydney Declaration (Revisiting the essence of forensic science through its fundamental principles). In Italy, however, reflections on the “validity” of evidentiary results remain limited, particularly regarding the concept of measurement uncertainty and the criteria for its evaluation. The project, concluded at the end of 2025, sought to help fill this gap.

The Department of Industrial Engineering (DII) of the University of Trento participated in the research, coordinated by Prof. Di Paolo of the Faculty of Law, providing methodological expertise in metrological aspects. The University of Insubria and the Polytechnic University of Milan also collaborated.

From case study analysis to operational guidelines

The first phase of the research highlighted, also through case studies, the main critical issues that scientific evidence raises in judicial practice. Subsequently, the possible contributions of metrology were analyzed in the most delicate evidentiary stages of criminal proceedings.

From this theoretical and applied analysis emerged best practices and operational guidelines aimed at ensuring the proper and effective use of metrological concepts in criminal adjudication. The research outcomes were published in leading scientific journals and collected in a White Paper available on the project website: https://www.giurisprudenza.unitn.it/4642/prin-2022.

The results achieved may foster the dissemination of a new evidentiary culture based on “methodical doubt,” essential for preventing cognitive biases and judicial errors. They also contribute to building a shared vocabulary between legal professionals and technical-scientific experts, facilitating mutual understanding and promoting greater awareness of the intrinsic limits of scientific evidence.

As illustrated in the White Paper, applying metrological principles across the various fields of forensic science represents significant added value. Metrology makes it possible to identify, quantify, and express the uncertainty inherent in every measurement result, ensuring transparency, reliability, and reproducibility in scientific investigations and strengthening the epistemological robustness of technical knowledge used in judicial proceedings.

Contemporary reality constantly exposes us to decisions in highly complex contexts, from pandemic management to climate model projections, and to high-profile judicial cases that have made clear how delicate the relationship is between scientific knowledge, uncertainty, and decision-making processes.

Transferring to the judicial world an awareness of the intrinsic limits of science is therefore not only appropriate but crucial. Accepting that uncertainty can be quantified and managed, but never completely eliminated, reduces the risk that investigative results will be interpreted as absolute truths. Those who prosecute and those who judge must be able to distinguish the degree of reliability of available information, understanding the weight and limits of the scientific methods and tools employed, as well as the impact of potential cognitive biases affecting both experts and legal practitioners.

From this perspective, metrological culture emerges as a fundamental safeguard against judicial errors and as a qualifying contribution that the DII offers to interdisciplinary dialogue between science and law.