What goes around comes around: why the critique of expert-led integral bayesian modelling also undermines judge-led bayesian modelling

• Pages: 225-232
• Date: 01 July 2026
• Published date: 01 July 2026
• Author: Bojan Spaic
• Subject Matter: Derecho Procesal

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

Año 2026 11 pp. 225-232 DOI: 10.33115/udg_bib/qf.i11.23292

Quaestio facti. Revista Internacional sobre Razonamiento Probatorio

Quaestio facti. International Journal on Evidential Legal Reasoning

Sección: Conjeturas y refutaciones

2026 l 11 pp. 225-232

Madrid, 2026

DOI: 10.33115/udg_bib/qf.i11.23292

Marcial Pons Ediciones Jurídicas y Sociales

© Bojan Spaić

ISSN: 2604-6202

Recibido: 28/05/2026 | Aceptado: 12/06/20266 | Publicado online: 30/06/2026

Editado bajo licencia Reconocimiento 4.0 Internacional de Creative Commons

WHAT GOES AROUND COMES AROUND: WHY THE CRITIQUE

OF EXPERT-LED INTEGRAL BAYESIAN MODELLING ALSO

UNDERMINES JUDGE-LED BAYESIAN MODELLING*

Bojan Spaić

University of Belgrade Faculty of Law

ABSTRACT: is article oers an internal refutation of Anne Ruth Mackor’s defence of court-led

integral Bayesian modelling in criminal adjudication. Mackor usefully distinguishes between the

now well-established Bayesian treatment of individual items of forensic evidence and the more

controversial Bayesian modelling of criminal cases as a whole. She also convincingly argues that

expert-led whole-case modelling is objectionable because the expert must select hypotheses, evi-

dence, dependencies, and probabilistic inputs in a manner that eectively places the expert in the

judge’s chair. Yet she maintains that this objection applies with less force when whole-case Bayesian

modelling is performed by judges themselves, especially as an internal “means of inspection” or

“sharpening” device and with the support of a forensic adviser. is article argues that the distinc-

tion fails. e decisive objection to integral Bayesian modelling does not arise merely from the

formal identity of the modeller. It lies in the modelling choices themselves being adjudicatively

decisive. ose choices remain no less decisive when made by judges, and the involvement of the

forensic adviser reintroduces, in a less visible form, the very institutional concern Mackor’s critique

seeks to avoid.

KEYWORDS: evidential reasoning; legal probabilism; legal abductivism; Anne Ruth Mackor.

* is paper is a contribution to the 2026 annual strategic project of the Faculty of Law University

of Belgrade “Problems of creation, interpretation and application of law.”