Two Meanings of ‘Reasonableness’: Dispelling the ‘Floating’ Reasonable Doubt
| Author | Federico Picinali |
| Date | 01 September 2013 |
| DOI | http://doi.org/10.1111/1468-2230.12038 |
| Published date | 01 September 2013 |
Two Meanings of ‘Reasonableness’:
Dispelling the ‘Floating’ Reasonable Doubt
Federico Picinali*
The ‘reasonable doubt standard’ is the controlling standard of proof for criminal fact finding in
several jurisdictions. Drawing on decision theory, some scholars have argued that the stringency
of this standard varies according to the circumstances of the case. This article contends that the
standard does not lend itself to the ‘sliding-scale’ approach mandated by decision theory. This is
supported through investigation of the concept of ‘reasonableness’. While this concept has mostly
been studied as it operates with reference to practical reasoning, scant attention has been given to
the meaning that it acquires when referred to theoretical reasoning. Unlike in the former case,
reasonableness does not in the latter depend on the reasoner’s attitudes in favour of the outcomes
of a decisional process. Therefore, since criminal fact finding is an instance of theoretical
reasoning, the question whether in this enterprise a doubt is reasonable is not susceptible to a
decision-theoretic approach.
INTRODUCTION
Several jurisdictions adopt the ‘reasonable doubt standard’ as the standard
of proof for criminal proceedings.1The choice is traditionally justified on
consequentialist grounds. A high standard of proof is selected because, in
Blackstone’s terms, ‘it is better that ten guilty persons escape, than that one
innocent suffer.’2Leaving the numbers aside, the maxim compares the false
negative and false positive outcomes of a criminal trial, that is, respectively,
acquitting the guilty and convicting the innocent. The comparison expresses a
judgment on the relative worths of the two outcomes. It clearly communicates
that the conviction of the innocent is far worse than the acquittal of the guilty;
thus, the need to make the former outcome considerably less likely to happen
*Law Department, London School of Economics and Political Science. I am indebted to Anna Ichino,
Kate Stith, Peter Tillers, Jim Franklin, Katie Steele, Michael Risinger, James Whitman, Manolis
Melissaris, Steven Duke, Paddy Long, Melania Villa and participants in the LSE Choice Group Seminar
for valuable comments on earlier versions of this paper. I am particularly grateful to the MLR readers
for their helpful feedback during the review process.
1 Notably, the English Crown Court Bench Book 2010, ch 4, s 3 advises judges to instruct jurors by
using the ‘be sure of guilt’ standard, as opposed to the reasonable doubt standard. However, it also
clarifies that ‘being sure is the same as entertaining no reasonable doubt’ (see Judicial Studies Board,
Crown Court Bench Book: Directing the Jury (2010), at http://www.judiciary.gov.uk/Resources/
JCO/Documents/Training/benchbook_criminal_2010.pdf (last visited 25 June 2013)).
2 See W. Blackstone, Commentaries on the Laws of England vol 4 (1769, Chicago: University of
Chicago Press, 1979) 352. The maxim predates William Blackstone: see Judge May, ‘Some Rules
of Evidence. Reasonable Doubt in Civil and Criminal Cases’ (1875) 10 American Law Review 642,
653, 654 and M. D. Risinger, ‘John Henry Wigmore, Johnny Lynn Old Chief, and “Legitimate
Moral Force”: Keeping the Courtroom Safe for Heartstrings and Gore’ (1998) 49 Hastings Law
Journal 403, 442, 443.
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© 2013 The Author. The Modern Law Review © 2013 The Modern Law Review Limited. (2013) 76(5) MLR 845–875
Published by John Wiley & Sons Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA
than the latter, through setting a very demanding standard of proof for the
prosecution’s case.
An application of this consequentialist reasoning can be found in the concur-
ring opinion of Justice Harlan in In re Winship3– the celebrated decision of the
American Supreme Court that laid the foundations of the reasonable doubt
standard in the Fifth Amendment of the American Constitution. Harlan argues
that:
[b]ecause the standard of proof affects the comparative frequency of these two types
of erroneous outcomes [ie, convicting the innocent and acquitting the guilty], the
choice of the standard to be applied in a particular kind of litigation should, in a
rational world, reflect an assessment of the comparative social disutility of each . . .
In a criminal case . . . we do not view the social disutility of convicting an innocent
man as equivalent to the disutility of acquitting someone who is guilty . . . In this
contest [we] view the requirement of proof beyond a reasonable doubt in a criminal
case as bottomed on a fundamental value determination of our society that it is far
worse to convict an innocent man than to let a guilty man go free.4
Harlan’s words flesh out the premise as well as the implication of Blackstone’s
maxim. Moreover, the terminology adopted in the passage clearly places the
maxim in the theoretical framework where it belongs: decision theory.
This paper explores one consequence of the decision-theoretic approach to
the selection of the criminal standard of proof: the standard’s variability. As will
be shown, decision theory implies that the standard of proof should be higher in
some criminal cases than in others. In order to understand why, it is necessary
first to examine this theory in more detail.
THE EXPECTED UTILITY FRAMEWORK
The basic tenet of decision theory is that a free and rational agent ought to
choose the course of action yielding the highest ‘expected utility’, defined as the
product of the utility of a certain outcome and the probability that such outcome
occurs.5In order to apply this tenet to the situation of an adjudicator in a criminal
trial one needs to consider the potential outcomes thereof and their respective
utilities. Harlan’s approach, focusing exclusively on the erroneous outcomes, is
an incomplete implementation of decision theory.6A satisfactory account should
instead encompass all four possible outcomes of a trial: the conviction of the
guilty (cg), the conviction of the innocent (ci), the acquittal of the guilty (ag), and
the acquittal of the innocent (ai).
3In re Winship [1970] 397 US 358.
4ibid, 371–372 (Harlan, J, concurring).
5 See J. Kaplan, ‘Decision Theory and the Factfinding Process’ (1968) 20 Stanford Law Review 1065,
1069.
6 See E. Lillquist, ‘Recasting Reasonable Doubt: Decision Theory and the Virtues of Variability’
(2002) 36 UC Davis Law Review 85, 107–111 and L. Laudan and H. D. Saunders, ‘Rethinking the
Criminal Standard of Proof: Seeking Consensus about the Utilities of Trial Outcomes’ (2009) 7
International Commentary on Evidence 1, 3, 4.
Two Meanings of ‘Reasonableness’
© 2013 The Author. The Modern Law Review © 2013 The Modern Law Review Limited.
846 (2013) 76(5) MLR 845–875
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