In defence of subjectivity: extending the argument for a transparent trial. (A support on "bayesian modelling of criminal cases as a whole. A philosophical reflection on dutch case law")

• Pages: 143-156
• Date: 01 July 2026
• Published date: 01 July 2026
• Author: Silvia Bozza,Franco Taroni,Colin Aitken
• Subject Matter: Derecho Procesal

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio / International Journal on Evidential Legal Reasoning

Año 2026 11 pp. 143-156 DOI: 10.33115/udg_bib/qf.i11.23268

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio

Quaestio facti. International Journal on Evidential Legal Reasoning

Sección: Conjeturas y refutaciones

2026 l 11 pp. 143-156

Madrid, 2026

DOI: 10.33115/udg_bib/qf.i11.23268

Marcial Pons Ediciones Jurídicas y Sociales

© Silvia Bozza

© Franco Taroni

© Colin Aitken

ISSN: 2604-6202

Recibido: 06/02/2026 | Aceptado: 07/05/2026 | Publicado online: 29/05/2025

Editado bajo licencia Reconocimiento 4.0 Internacional de Creative Commons

IN DEFENCE OF SUBJECTIVITY:

EXTENDING THE ARGUMENT FOR A TRANSPARENT TRIAL.

(A SUPPORT ON “BAYESIAN MODELLING OF CRIMINAL

CASES AS A WHOLE. A PHILOSOPHICAL REFLECTION

ON DUTCH CASE LAW”)

Silvia Bozza*

Franco Taroni**

Colin Aitken***

ABSTRACT: is comment addresses the “prior challenge” in forensic Bayesian modelling, recently

highlighted by Anne Ruth Mackor (2026). We argue that the perceived lack of frequency data is

not an insurmountable obstacle but a misconception rooted in an outdated view of probability. By

adopting a radical subjectivist perspective based on de Finetti’s teachings, we reframe probability

as a coherent representation of a decision-maker’s state of knowledge. We advocate for a strict

functional separation: forensic experts provide the likelihood ratio based on technical ndings,

while the court assigns prior odds based on the specic case context. rough sensitivity analysis,

we demonstrate that the subjectivity of priors can be viewed not as a source of arbitrariness but

rather as a transparent and auditable mechanism that enhances judicial accountability. Ultimately,

the Bayesian model is presented as a logical necessity for preventing miscarriages of justice.

KEYWORDS: bayesian modelling; forensic science; subjective probability.

* Department of Economics, Ca’ Foscari University of Venice, Venice, Italy. School of Criminal

Justice, University of Lausanne, Lausanne, Switzerland. E-mail: Silviab@unive.it, Silvia.Bozza@unil.ch.

** School of Criminal Justice, University of Lausanne, Lausanne, Switzerland. E-mail: Franco.

Taroni@unil.ch.

*** School of Mathematics and the Maxwell Institute of Mathematical Sciences, e University of

Edinburgh, Edinburgh, United Kingdom. E-mail: C.Aitken@ed.ac.uk.