Is the Expert Admissibility Game Fixed?: Judicial Gatekeeping of Fire and Arson Evidence

• DOI: http://doi.org/10.1111/lapo.12047
• Date: 01 January 2016
• Author: Rachel Dioso‐Villa
• Published date: 01 January 2016

Is the Expert Admissibility Game Fixed?: Judicial

Gatekeeping of Fire and Arson Evidence

RACHEL DIOSO-VILLA

Anecdotal evidence claims that in criminal cases, trial judges admit the prosecution’s expert

witnesses more readily than the defendants’, and in civil cases the reverse is true; judges exclude

plaintiffs’ experts more often than civil defendants’ experts. This occurs despite the fact that,

with few exceptions, the same rules of admissibility apply to all parties and, in most jurisdictions,

across criminal and civil cases. This article empirically tests this differential by reviewing judicial

decisions to admit or exclude evidence holding the type of expert testimony constant, fire and

arson evidence, across criminal and civil cases in the United States. The study examines the

admissibility of fire and arson investigation experts in criminal and civil cases across all legal

parties in fifty-seven federal and state opinions in the United States. The findings offer empirical

support of a bias in criminal cases and in civil cases which present expert witnesses at trial, and

is less pronounced, but still evident, on appeal. Specifically, the role of the party that offers the

evidence has a profound effect on whether arson evidence is admitted, even when factors around

the judge’s political affiliation, attorney experience, expert qualifications, and rules of evidence

are taken into account.

I have a hypothesis. It is falsifiable, and if someone wants to do the empirical work, we could

establish error rates, subject our methodology to peer review—the whole nine yards. The

results would be admissible in any court of law, satisfying even the strictest Daubert

interpretation. But the courts will not like it. I suspect that, almost regardless of the quality of

the science involved, judges tend to admit scientific evidence when it favors the prosecution

while refusing to admit it when it favors the defense. (Rozelle 2007, 597)

Contrary to the very strict scrutiny some federal courts apply when plaintiffs’ experts seek to

testify, it should be noted that they seem to require considerably less with regard to prosecu-

tion experts in criminal cases. This is so even though in criminal proceedings, the prosecution

must meet a much higher standard of proof [. . ..] Nevertheless, although courts often exclude

plaintiffs’ experts in toxic tort cases, courts virtually always permit a prosecution expert to

testify after a Daubert challenge. (Berger 2005, S63)

INTRODUCTION

Expert witnesses can provide prosecutors and plaintiffs with the required expert testimony

to successfully prove their claims and argue their cases in court. Likewise, criminal and

civil defendants use expert witnesses to defend themselves against claims and charges

raised against them at trial. During a trial, judges make a multitude of decisions that do

Simon Cole and Lisa Broidy provided valuable feedback on earlier drafts and the three anonymous reviewers,

and Editor, Nancy Reichman, provided insightful comments and suggestions.

Address correspondence to: Rachel Dioso-Villa, Griffith University, School of Criminology and Criminal

Justice and Griffith Criminology Institute, 176 Messines Ridge Rd., M10_3.29, Mt. Gravatt, QLD 4012

Australia. Telephone: +61 (0)7 3735 1096; E-mail: r.diosovilla@griffith.edu.au.

LAW & POLICY, Vol. ••, No ••, •• 2015 ISSN 0265–8240

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doi: 10.1111/lapo.12047

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doi: 10.1111/lapo.12047

not speak directly to the case outcome but influence it nonetheless. The decision to admit

or exclude an expert witness falls squarely in this category. Allowing a party to present

their experts foreseeably strengthens an argument, while excluding experts can impede it,

indirectly shaping case outcomes. If there is judicial bias that favors specific legal parties

over others in these decisions, then this raises uncertainty about the legitimacy and

fairness of the justice system; it would make for an unequal legal playing field.

Anecdotal evidence and a handful of empirical studies suggest that judges are

seamlessly admitting the government’s expert witnesses in criminal trials and are routinely

scrutinizing the admission of plaintiffs’ experts in civil cases (Edmond and Roach 2011;

Edmond and Roberts 2011; Dwyer 2007; Rozelle 2007; Berger 2005; Edmond and Mercer

2004; Risinger 2000). Berger (2005) reiterates this notion that trial judges “virtually always

permit a prosecution’s expert to testify,” while they often exclude plaintiffs’ experts by

applying “very strict scrutiny” to the evidence (Berger 2005, S63). As Rozelle (2007) points

out in the epigraph above, judicial bias operates independently of relevant legal rules and

irrespective of the quality of expert evidence. The result is that admissibility decisions are

made on other factors, independent of the scientific basis of the expertise or the case facts

that may unduly disadvantage specific legal parties, making “[t]he game of scientific

evidence look fixed” (Rozelle 2007, 598).

This imbalance, which claims that courts demonstrate leniency in the admission of expert

witnesses in the prosecution of criminal cases, whereas they are rigorous in their evaluation

of plaintiffs’ experts in civil cases, is counter to a strict legalistic view of the law. Moreover,

to the extent that there is bias, one might expect that the standards of evidence are stricter

when life and liberty in criminal cases are at stake compared to financial liability or

monetary loss at risk in civil litigation (Allen 2003; Nance 2003). This differentiation would

reflect the higher standard of proof in criminal than civil cases, and law’s claim that it is far

worse to wrongfully convict innocent people than it is to have inaccurate civil judgments

(Risinger 2000). Moreover, in a perfectly fair or unbiased system, one would expect no

differentiation across legal parties or case type. However, the limited evidence suggests that

not only is there bias, but it operates to protect those with greater social, political, and legal

power than those most vulnerable. The evidence, however, is both limited and contentious.

This study aims to impose a more rigorous empirical lens on the question of whether judges

apply rules of evidence in ways that favor certain legal parties over others and is the first step

in the process of unpacking whether there is bias and why and how it operates. Focusing on

judicial rulings regarding the admission of expert testimony in criminal and civil arson

cases, I test claims that defendants are disadvantaged in criminal cases, while plaintiffs are

disadvantaged in civil cases. Support for this hypothesis would suggest that extralegal

considerations influence the interpretation and application of rules of evidence in ways that

disadvantage the more vulnerable legal party.

RULES REGARDING THE ADMISSION OF EVIDENCE

Trial judges serve as the courts’ gatekeepers to scrutinize the admission of expert evidence.

The US Supreme Court in Daubert v Merrell Dow Pharmaceuticals, Inc. (1993) enlisted

trial judges to test the relevance and reliability of expert evidence to ensure that junk

science is excluded from courts (Faigman 1999; Foster and Huber 1999; Huber 1991).1

With few exceptions, admissibility rulings in the United States follow either Daubert

standards, Frye’s general acceptance test that requires that the expert evidence is accepted

by its scientific community (Frye v United States 1923), or a combination of Daubert and

Frye guidelines, specific to a particular state (Edmond et al. 2013; Lustre 2001). These tests

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