Quantifying Reasonable Doubt

Rutgers University Law Review, Vol. 72, Issue 2 (Forthcoming 2020)

49 Pages Posted: 18 Aug 2018 Last revised: 15 Sep 2019

See all articles by Daniel Pi

Daniel Pi

Mitchell Hamline School of Law

Francesco Parisi

University of Minnesota - Law School; University of Bologna

Barbara Luppi

University of St. Thomas School of Law; Università degli studi di Modena e Reggio Emilia (UNIMORE) - Faculty of Business and Economics

Date Written: August 5, 2018

Abstract

This article contributes in three ways to the prior literature on the reasonable doubt standard. First, it synthesizes the insular strands of historical, economic, jurisprudential, and doctrinal scholarship on reasonable doubt. Second, it advances a conception of the criminal standard of proof designed to avoid the various problems affecting earlier attempts to devise meaningful definitions of reasonable doubt. The definition proposed is that “reasonable doubt” be the standard of proof which minimizes the aggregate subjective expected social cost of false conviction and false acquittal. Judicial pronouncements of Blackstonian ratios (for example, that it is better that ten guilty go free than one innocent be convicted) are interpreted as judicial estimates of these variables, from which efficient reasonable doubt standards may be calculated. It is urged that courts adopt the precise numerical measures of certainty in jury instructions (for example, that a juror should only vote to convict if he is more than x% certain of the defendant’s guilt). Judicial pronouncements of Blackstonian ratios are collected from the caselaw of all fifty states and federal courts to encourage practitioners to test the refined conception in their jurisdiction.

Keywords: Reasonable Doubt, Standard of Proof, Blackstone's Ratio

JEL Classification: K14, K41

Suggested Citation

Pi, Daniel and Parisi, Francesco and Luppi, Barbara, Quantifying Reasonable Doubt (August 5, 2018). Rutgers University Law Review, Vol. 72, Issue 2 (Forthcoming 2020). Available at SSRN: https://ssrn.com/abstract=3226479 or http://dx.doi.org/10.2139/ssrn.3226479

Daniel Pi (Contact Author)

Mitchell Hamline School of Law ( email )

875 Summit Ave
St. Paul, MN 55105-3076
United States

Francesco Parisi

University of Minnesota - Law School ( email )

229 19th Avenue South
Minneapolis, MN 55455
United States

University of Bologna ( email )

Piazza Scaravilli 1
40126 Bologna, fc 47100
Italy

Barbara Luppi

University of St. Thomas School of Law

2115 Summit Avenue
Saint Paul, MN 55105
United States

Università degli studi di Modena e Reggio Emilia (UNIMORE) - Faculty of Business and Economics ( email )

Viale Berengario 51
41100 Modena, Modena 41100
Italy

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