Statistical Evidence, Assertions and Responsibility
| DOI | http://doi.org/10.1111/1468-2230.12404 |
| Published date | 01 March 2019 |
| Author | Liat Levanon |
| Date | 01 March 2019 |
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Statistical Evidence, Assertions and Responsibility
Liat Levanon∗
The legal system has been ambivalent about naked statistical evidence. Addressing this am-
bivalence, the article explores the epistemological status of naked statistical evidence and its
normative and practical implications. It is suggested that since naked statistical evidence cannot
generate knowledge, it cannot be the basis for assertions of facts; and assertions of facts are
practically and legally important: they are essential in order to establish the court’sresponsibility
for its decisions and its errors. Such responsibility is needed in order to maintain the legitimacy
of the legal system; to avoid unfairness to defendants; and to ensure that legal decision-makers
have no valid claims against the decision-making arrangement. As a result, the legal system is
inclined to avoid statistical evidence altogether.
INTRODUCTION
Advances in the social sciences in recent decades may have an unprecedented
impact on legal modes of proof. The use of statistical methods to analyse human
behaviour has resulted in the accumulation of data that has the potential to
alter the way in which facts are legally established. These statistical data are
now readily available for use as legal evidence. If research establishes that, say,
males of a certain race and age are more likely than random members of
the population to commit certain types of crimes, these data may well have
probative value in a trial against such a defendant for such an offence. But
advances in social sciences have not only added statistical data to the traditional
evidential substrate of trials; they have also stimulated rethinking of traditional
evidence and modes of proof. After all, much like the newly accumulated
statistical data, traditional evidence such as eyewitness testimony can also be
described in statistical terms.1The potential impact on legal f act-finding is
therefore hard to ignore.
The legal system has found itself bewildered by these advances. It has
remained suspicious about full incorporation of the new statistical data in
trials,2but the grounds for this suspicion have proven hard to articulate. Much
effort has been invested in the attempt to explain how the new data, which
∗The Dickson Poon School of Law, King’s College London. This article has benefitted greatly from
comments by Federico Picinali, Amit Pundik and Paul Roberts. Special thanks, as always, to David
Enoch for his support and encouragement and for his contribution to the development of my ideas
in this article. I am also indebted to two anonymous reviewers for generous and invaluable assistance
in bringing the piece to its current for m.
1 See P. Tillers, ‘If Wishes Were Horses: Discursive Comments on Attempts to Prevent Individuals
from Being Unfairly Burdened by Their Reference Classes’ (2005) 4 Law, Probability and Risk
33.
2 This suspicious attitude finds expression in the provisionsregulating the admissibility of propensity
evidence in the Criminal Justice Act 2003, s 101(1), and in the broad discretion left for trial judges
in interpreting these provisions.
C2019 The Author.The Moder n Law Review C2019 The Modern Law Review Limited. (2019) 82(2) MLR 269–292
Published by JohnWiley & Sons Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK and 101 Station Landing, Medford, MA 02155, USA
Statistical Evidence, Assertions and Responsibility
has been termed ‘naked statistical evidence’ (NSE), is different from traditional
evidence.3Some of the explanations are epistemological, demonstrating
that NSE cannot generate knowledge. Other explanations are normative or
practical, demonstrating that admission of NSE is undesired for ethical reasons
or for policy reasons. In an insightful paper, David Enoch, Levi Spectre and
Talia Fisher have claimed that knowledge has no legal value, but they have
sought to demonstrate that epistemological and practical explanations are not
totally independent of each other. The authors have further suggested that a
deeper story about the relation between the two is yet to be told.4
The article advances the argument that knowledge does have legal value:
knowledge is the only possible foundation for legal assertions of liability and
guilt, and assertions, in turn, guarantee the court’s responsibility for its decisions
and indeed for its errors. Responsibility is needed in order to maintain the
legitimacy of the legal system, to avoid unfairness to defendants, and to ensure
that decision-makers have no valid claims against the legal decision-making
arrangement in cases of error. Since NSE cannot generate knowledge, decisions
based on NSE cannot be the basis for assertions of liability and guilt and
accordingly cannot give rise to the court’s responsibility for errors. For this
reason, the legal system is inclined to avoid relying on NSE altogether.
To unfold this argument, the article proceeds in four parts. The first part
presents the problem. It discusses two of the main existing accounts of the con-
ditions of knowledge that NSE fails to fulfil, namely the sensitivity condition5
and the normic support condition.6It is demonstrated that these accounts do
not explain why knowledge might be valuable for legal decision-making.
The second part starts considering the value of knowledge for legal decision-
making. It advances the argument that legal decision-making (as we know it)
involves assertions of liability and guilt and accordingly is subject to Timo-
thy Williamson’s knowledge norm of assertion.7Legal decision-making must
3 See D. Enoch, L. Spectre and T. Fisher, ‘Statistical Evidence, Sensitivity, and the Legal Value
of Knowledge’ (2012) 40 Philosophy and Public Affairs 197; D. Enoch and T. Fisher, ‘Sense and
“Sensitivity”: Epistemic and Instrumental Approaches to Statistical Evidence’ (2015) 67 Stanford
Law Review 557; A. Stein, Foundations of Evidence Law (New York, NY and Oxford: OUP, 2005)
80-91; M. Smith, Between Probability and Certainty: What Justifies Belief (Oxford and New York,
NY: OUP, 2016); M. S. Pardo, ‘Safety vs. Sensitivity: Possible Worlds and the Law of Evidence’
(2018) 24 Legal Theory (forthcoming); D. T. Wasserman, ‘The morality of Statistical Proof and the
Risk of Mistaken Liability’ (1991) 13 Cardozo Law Review 935; A. Pundik, ‘Statistical Evidence
and Individual Litigants: A Reconsideration of Wasserman’s Argument from Autonomy’ (2008)
12 International Journal of Evidence and Proof 303; A. Pundik, ‘Freedom and Generalisaion’ (2016)
37 OJLS 189; A. Pundik, ‘Against Racial Profiling’ (2017) 67 UTLJ 175; C. R. Nesson, ‘The
Evidence or the Event? On JudicialProof and the Acceptability of Verdicts’ (1985) 98 Harv L Rev
1357, 1378; F. Picinali, ‘Generalisations, Casual Relationships, and Moral Responsibility’ (2016)
20 The International Journal of Evidence and Proof 121; R. W. Wright, ‘Causation, Responsibility,
Risk, Probability, Naked Statistics, and Proof: Pruning the Bramble Bush by Clarifying the
Concepts’ (1998) 73 Iowa L Rev 1001, 1054.
4 Enoch, Spectre, and Fisher, ibid, 220-221.
5 See Enoch, Spectre and Fisher, ibid.
6 See Smith, n 3 above.
7 T. Williamson, ‘Knowing and Asserting’ (1996) 105 Philosophical Review 489, 494; see also T.
Williamson, Knowledge and Its Limits (Oxford: OUP, 2000). Many have accepted Williamson’s
knowledge norm of assertion, including, for example, J. Hawthorne, Knowledge and Lotteries
270 C2019 The Author. The Modern Law Review C2019 The Modern Law Review Limited.
(2019) 82(2) MLR 269–292
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