Court‐appointed experts and accuracy in adversarial litigation

Published date01 September 2020
DOIhttp://doi.org/10.1111/ijet.12191
Date01 September 2020
doi: 10.1111/ijet.12191
Court-appointed experts and accuracy in
adversarial litigation
Chulyoung Kimand Paul S. Koh
Concerned about distortion of evidence arising from litigants’ strong incentive to misrepresent
information provided to fact-finders, legal scholars and commentators have long suggested
that courts appoint their own advisors for neutral information regarding disputes. This paper
examines the litigants’ problem of losing incentive toprovide information when judges seek the
advice of court-appointed experts. Within a standard litigation-game framework, we find that
assigning court-appointed experts involves a trade-off: although such experts help judges obtain
more information overall, thereby reducing the number of errors during trials, they weaken
litigants’ incentive to supply expert information, thus undermining the adversarial natureof the
current American legal system.
Key wor ds litigation game, court-appointed expert, persuasion game, evidence distortion
JEL classification C72, D82, K41
Accepted 30 January 2018
1 Introduction
The current American legal system is adversarial and requires litigants to provide information to a
judge for decision-making. This decentralized method of collecting information has been praised by
many scholars,including Posner (1988, 1999) who presented strong arguments for such decentralized
institutions. In general, economic analysis has supported such decentralized systems of evidence
collection. The main intuition obtained from various economic models, as demonstrated in an early
contribution by Milgrom and Roberts (1986), is that information held by litigants is eventually
revealed to the fact-finder because of the competition between them: a piece of evidence detrimental
to one party is beneficial to the other, and therefore one of the competing parties eventually reveals
any relevant evidence. This intuition has been confirmed to be robust in a more general environment
and has strongly supported the current form of the American legal system.1
School of Economics, YonseiUniversity, Seoul, Korea.Email: chulyoung.kim@gmail.com
Department of Economics, Columbia University,New York, USA.
Weare grateful to Albert Choi, Navin Kartik, Jeong-YooKim, and an anonymous referee for their valuable comments. All
remaining errors are our own.
1Milgrom and Roberts (1986) employ a persuasion-game framework for their analysis. See, among others, Froeb and
Kobayashi (1996), Shin (1998), Demougin and Fluet (2008), and Kim (2014a, 2017a) for the same line of research. See
also Froeb and Kobayashi (2001), Parisi (2002), Emons and Fluet (2009a,b), and Pavesi and Scotti (2014) for related
research. While these papers assume that the litigants always supply biased information to the fact-finder,Kim (2016)
studies a situation in which a litigant is willing to provide unbiased information. Kim (2017b) studies a situation in which
the fact-finder does not observe the quality of information proffered by the litigants.
International Journal of Economic Theory XX (2018) 1–24 © IAET 1
International Journal of Economic Theory
International Journal of Economic Theory 16 (2020) 282–305 © IAET
282
Accuracy in adversarial legislation Chulyoung Kim and Paul S. Koh
Despite decentralization being strongly supported in evidence collection, both scholars and
practitioners have long noted its shortcomings, particularly its contribution to evidence distortion,
because competing litigants have strong incentivesto misrepresent their evidence and thus influence
the courts’ final decisions. Thus, there have been numerous reform proposalssuggesting that courts
appoint their own experts, thereby enhancing the inquisitorial component in the American legal
system.2A large body of literature has examined these issues and presented various proposals;
see, for example, Epstein (1992, 1993), Cecil and Willging (1994), Faigman (1996), Pinsky (1997),
Deason (1998), and Reisinger (1998) for arguments that promote the use of court-appointed experts.
Erichson (1998) and Bernstein (2008) have suggested that judges use court-appointed experts as
advisors on issues such as the admissibility of scientific evidence rather than using them as sources
of information.
The general idea behind these proposals is simple yet compelling: by appointing a court advisor,
judges have access to a piece of neutral evidence that can help them determine the nature of disputes
more accurately, thereby increasing the accuracy of their final decisions. However, this reasoning
could be flawed because it fails to consider the ways in which litigants may alter their behavior in
response to the appointment of court advisors. In this paper we demonstrate, within the standard
litigation-game framework, that the presence of court-appointed experts weakens litigants’ incentive
to collect and provide evidence to judges. Moreprecisely, litigants expect that the expert information
provided by them will have little influence on judges’ decisions if judges obtain outside information
from court-appointed experts. Our primary results show that this expectation weakens litigants’
incentive to provide expert information in equilibrium. We also show that, despite receiving less
information from the litigants, judges obtain more information about the issues in disputes overall
when court-appointed experts are present; therefore, they make fewerer rorsdur ing decision-making
in equilibrium. Thus, using court-appointed experts entails a trade-off: although these experts help
judges obtain more information overall, thereby reducing the number of errors at trial, they weaken
litigants’ incentive to provide their expert information, thus undermining the adversarial nature of
the current American legal system.
To the best of our knowledge, no prior theoretical research has examined the effect of court-
appointed experts on litigants’ behavior. Papers byShin (1998) and Kim (2014a, 2017a), who com-
pare the decentralized and centralized systems of information provision in the persuasion-game
framework, are closely related to our research. In their papers, only the litigants provideinfor mation
to the judges in the decentralized system while the judges themselves acquire information in the
centralized system. In contrast, in our paper, weexamine an integr atedsystem in which both private
and court-appointed experts are allowed in courtrooms.
Using a principal–agent model, Dewatripont and Tirole (1999), Palumbo(2001, 2006), Iossa and
Palumbo (2007), Deffains and Demougin (2008), and Kim (2014b) examined whether decentralized
systems can provide information to fact-finders at a lower cost.These models strongly suppor t decen-
tralized systems, showing that incentive constraints can be easily overcomeby exploiting competition
among agents. Demougin and Fluet (2008) and Emons and Fluet (2009b) indicated how expanding
the role of judges in collecting information from litigants can improve decision-making. Froeb and
2See, for example, Runkle (2001), who discusses the structure of the Court Appointed Scientific Experts Program created
by the American Association for the Advancementof Science to help judges obtain independent experts. See also Hillman
(2002), Adrogue and Ratliff (2003), and Kaplan(2006), among others. Based on his experience as Judge Richard Posner’s
court-appointed economic expert, Sidak (2013) argues for court-appointed, neutral economic experts. Many reformers,
most famously including Hand (1901), have argued that the appropriate remedy for adversarial bias (combined with
inexpert juries) is increased reliance on court-appointed, non-partisan experts.
2International Journal of Economic Theory XX (2018) 1–24 © IAET
International Journal of Economic Theory 16 (2020) 282–305 © IAET 283

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