Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 11
The Admissibility of Expert
Testimony
marGareT a. berGer
Margaret A. Berger, J.D., was the Trustee Professor of Law, Brooklyn Law School, Brooklyn,
New York.
[Editor’s Note: While revising this chapter Professor Berger became ill and, tragically,
passed away. We have published her last revision, with a few edits to respond to
suggestions by reviewers.]
ConTenTs
I. Supreme Court Cases, 12
A. Daubert v. Merrell Dow Pharmaceuticals, Inc., 12
B. General Electric v. Joiner, 14
C. Kumho Tire Co. v. Carmichael, 16
D. Weisgram v. Marley, 18
II. Interpreting Daubert, 19
A. Atomization, 19
B. Conflating Admissibility with Sufficiency, 20
C. Credibility, 21
III. Applying Daubert, 22
A. Is the Expert Qualified? 22
B. Assessing the Scientific Foundation of Studies from Different
Disciplines, 23
C. How Should the Courts Assess Exposure? 25
IV. Forensic Science, 26
A. Validity, 27
B. Proficiency, 28
C. Malfunctioning Laboratories, 28
D. Interpretation, 29
E. Testimony, 29
F. Assistance for the Defense and Judges, 29
G. Confrontation Clause, 30
V. Procedural Context, 30
A. Class Certification Proceedings, 30
B. Discovery, 32
1. Amended discovery rules, 32
2. E-discovery, 34
C. Daubert Hearings, 35
VI. Conclusion, 36
11
OCR for page 12
Reference Manual on Scientific Evidence
I. Supreme Court Cases
In 1993, the Supreme Court’s opinion in Daubert v. Merrell Dow Pharmaceuticals1
ushered in a new era with regard to the admissibility of expert testimony. As
expert testimony has become increasingly essential in a wide variety of litigated
cases, the Daubert opinion has had an enormous impact. If plaintiffs’ expert proof is
excluded on a crucial issue, plaintiffs cannot win and usually cannot even get their
case to a jury. This discussion begins with a brief overview of the Supreme Court’s
three opinions on expert testimony—often called the Daubert trilogy2—and their
impact. It then examines a fourth Supreme Court case that relates to expert testi-
mony, before turning to a variety of issues that judges are called upon to resolve,
particularly when the proffered expert testimony hinges on scientific knowledge.
A. Daubert v. Merrell Dow Pharmaceuticals, Inc.
In the seminal Daubert case, the Court granted certiorari to decide whether the
so-called Frye (or “general acceptance”) test,3 which some federal circuits (and
virtually all state courts) used in determining the admissibility of scientific evi-
dence, had been superseded by the enactment of the Federal Rules of Evidence
in 1973. The Court held unanimously that the Frye test had not survived. Six
justices joined Justice Blackmun in setting forth a new test for admissibility after
concluding that “Rule 702 . . . clearly contemplates some degree of regulation of
the subjects and theories about which an expert may testify.”4 While the two other
members of the Court agreed with this conclusion about the role of Rule 702,
they thought that the task of enunciating a new rule for the admissibility of expert
proof should be left to another day.5
The majority opinion in Daubert sets forth a number of major themes that run
throughout the trilogy. First, it recognized the trial judge as the “gatekeeper” who
must screen proffered expert testimony.6 Second, the objective of the screening
is to ensure that expert testimony, in order to be admissible, must be “not only
relevant, but reliable.”7 Although there was nothing particularly novel about the
Supreme Court finding that a trial judge has the power to make an admissibility
determination—Federal Rules of Evidence 104(a) and 702 pointed to such a
conclusion—and federal trial judges had excluded expert testimony long before
1. 509 U.S. 579 (1993).
2. The other two cases are Gen. Elec. Co. v. Joiner, 522 U.S. 136 (1997) and Kumho Tire Co. v.
Carmichael, 526 U.S. 137 (1999). The disputed issue in all three cases was causation.
3. Frye v. United States, 293 F. 1013 (D.C. Cir. 1923).
4. Daubert, 509 U.S. at 589.
5. Id. at 601.
6. Id. at 589.
7. Id.
12
OCR for page 13
The Admissibility of Expert Testimony
Daubert, the majority opinion in Daubert stated that the trial court has not only
the power but the obligation to act as gatekeeper.8
The Court then considered the meaning of its two-pronged test of relevancy
and reliability in the context of scientific evidence. With regard to relevancy, the
Court explained that expert testimony cannot assist the trier in resolving a factual
dispute, as required by Rule 702, unless the expert’s theory is tied sufficiently to
the facts of the case. “Rule 702’s ‘helpfulness’ standard requires a valid scientific
connection to the pertinent inquiry as a precondition to admissibility.”9 This
consideration, the Court remarked, “has been aptly described by Judge Becker
as one of ‘fit.’”10
To determine whether proffered scientific testimony or evidence satisfies
the standard of evidentiary reliability,11 a judge must ascertain whether it is
“ground[ed] in the methods and procedures of science.”12 The Court, empha-
sizing that “[t]he inquiry envisioned by Rule 702 is . . . a flexible one,”13 then
examined the characteristics of scientific methodology and set out a nonexclusive
list of four factors that bear on whether a theory or technique has been derived
by the scientific method.14 First and foremost, the Court viewed science as an
empirical endeavor: “[W]hether [a theory or technique] can be (and has been)
tested” is the “methodology [that] distinguishes science from other fields of human
inquiry.”15 The Court also mentioned as indicators of good science whether the
technique or theory has been subjected to peer review or publication, whether
the existence of known or potential error rates has been determined, and whether
standards exist for controlling the technique’s operation.16 In addition, although
general acceptance of the methodology within the scientific community is no
longer dispositive, it remains a factor to be considered.17
The Court did not apply its new test to the eight experts for the plaintiffs
who sought to testify on the basis of in vitro, animal, and epidemiological studies
8. Id.
9. Id. at 591–92.
10. Id. at 591. Judge Becker used this term in discussing the admissibility of expert testimony
about factors that make eyewitness testimony unreliable. See United States v. Downing, 753 F.2d
1224, 1242 (3d Cir. 1985) (on remand court rejected the expert testimony on ground of “fit” because
expert discussed factors such as the high likelihood of inaccurate cross-racial identifications that were
not present in the case) and United States v. Downing, 609 F. Supp. 784, 791–92 (E.D. Pa. 1985),
aff’d, 780 F.2d 1017 (3d Cir. 1985).
11. Commentators have faulted the Court for using the label “reliability” to refer to the concept
that scientists term “validity.” The Court’s choice of language was deliberate. It acknowledged that
scientists typically distinguish between validity and reliability and that “[i]n a case involving scientific
evidence, evidentiary reliability will be based upon scientific validity.” Daubert, 509 U.S. at 590 n.9.
12. Id. at 590.
13. Id. at 594.
14. Id. at 593–94. “[W]e do not presume to set out a definitive checklist or test.” Id. at 593.
15. Id.
16. Id. at 593–94.
17. Id. at 594.
13
OCR for page 14
Reference Manual on Scientific Evidence
that the drug Bendectin taken by the plaintiffs’ mothers during pregnancy could
cause or had caused the plaintiffs’ birth defects. Instead, it reversed and remanded
the case. Nor did the Court deal with any of the procedural issues raised by the
Daubert opinion, such as the burden, if any, on the party seeking a ruling exclud-
ing expert testimony, or the standard of review on appeal.
The Daubert opinion soon led to Daubert motions followed by Daubert hear-
ings as parties moved in limine to have their opponents’ experts precluded from
testifying at trial for failure to satisfy the new requirements for expert testimony.
The motions raised numerous questions that the Court had not dealt with, some
of which were dealt with in the next two opinions by the Supreme Court.
B. General Electric v. Joiner
In General Electric Co. v. Joiner,18 the second case in the trilogy, certiorari was
granted in order to determine the appropriate standard an appellate court should
apply in reviewing a trial court’s Daubert decision to admit or exclude scientific
expert testimony. In Joiner, the 37-year-old plaintiff, a longtime smoker with a
family history of lung cancer, claimed that exposure to polychlorinated biphenyls
(PCBs) and their derivatives had promoted the development of his small-cell lung
cancer. The trial court applied the Daubert criteria, excluded the opinions of the
plaintiff’s experts, and granted the defendants’ motion for summary judgment.19
The court of appeals reversed the decision, stating that “[b]ecause the Federal
Rules of Evidence governing expert testimony display a preference for admis-
sibility, we apply a particularly stringent standard of review to the trial judge’s
exclusion of expert testimony.”20
All the justices joined Chief Justice Rehnquist in holding that abuse of discre-
tion is the correct standard for an appellate court to apply in reviewing a district
court’s evidentiary ruling, regardless of whether the ruling allowed or excluded
expert testimony.21 The Court unequivocally rejected the suggestion that a more
stringent standard is permissible when the ruling, as in Joiner, is “outcome deter-
minative” because it resulted in a grant of summary judgment for the defendant
because the plaintiff failed to produce evidence of causation.22 In a concurring
opinion, Justice Breyer urged judges to avail themselves of techniques, such as the
use of court-appointed experts, that would assist them in making determinations
about the admissibility of complex scientific or technical evidence.23
18. 522 U.S. 136 (1997).
19. Joiner v. Gen. Elec. Co., 864 F. Supp. 1310 (N.D. Ga. 1994).
20. Joiner v. Gen. Elec. Co., 78 F.3d 524, 529 (11th Cir. 1996).
21. Gen. Elec. Co. v. Joiner, 522 U.S. at 141–43.
22. Id. at 142–43.
23. Id. at 147–50. This issue is discussed in further detail in Justice Breyer’s introduction to
this manual.
14
OCR for page 15
The Admissibility of Expert Testimony
With the exception of Justice Stevens, who dissented from this part of the
opinion, the justices then did what they had not done in Daubert—they examined
the record, found that the plaintiff’s experts had been properly excluded, and
reversed the court of appeals decision without a remand to the lower court. The
Court concluded that it was within the district court’s discretion to find that the
statements of the plaintiff’s experts with regard to causation were nothing more
than speculation. The Court noted that the plaintiff never explained “how and
why the experts could have extrapolated their opinions”24 from animal studies
far removed from the circumstances of the plaintiff’s exposure.25 It also observed
that the district court could find that the four epidemiological studies the plaintiff
relied on were insufficient as a basis for his experts’ opinions.26 Consequently, the
court of appeals had erred in reversing the district court’s determination that the
studies relied on by the plaintiff’s experts “were not sufficient, whether individu-
ally or in combination, to support their conclusions that Joiner’s exposure to PCBs
contributed to his cancer.”27
The plaintiff in Joiner had argued that the epidemiological studies showed a
link between PCBs and cancer if the results of all the studies were pooled, and
that this weight-of-the-evidence methodology was reliable. Therefore, according
to the plaintiff, the district court erred when it excluded a conclusion based on a
scientifically reliable methodology because it thereby violated the Court’s precept
in Daubert that the “focus, of course, must be solely on principles and methodol-
ogy, not on the conclusions that they generate.”28 The Supreme Court responded
to this argument by stating that
conclusions and methodology are not entirely distinct from one another. Trained
experts commonly extrapolate from existing data. But nothing in either Daubert
or the Federal Rules of Evidence requires a district court to admit opinion evi-
dence which is connected to existing data only by the ipse dixit of the expert. A
court may conclude that there is simply too great an analytical gap between the
data and the opinion proffered.29
24. Id. at 144.
25. The studies involved infant mice that had massive doses of PCBs injected directly into their
bodies; Joiner was an adult who was exposed to fluids containing far lower concentrations of PCBs.
The infant mice developed a different type of cancer than Joiner did, and no animal studies showed that
adult mice exposed to PCBs developed cancer or that PCBs lead to cancer in other animal species. Id.
26. The authors of the first study of workers at an Italian plant found lung cancer rates among
ex-employees somewhat higher than might have been expected but refused to conclude that PCBs
had caused the excess rate. A second study of workers at a PCB production plant did not find the
somewhat higher incidence of lung cancer deaths to be statistically significant. The third study made
no mention of exposure to PCBs, and the workers in the fourth study who had a significant increase
in lung cancer rates also had been exposed to numerous other potential carcinogens. Id. at 145–46.
27. Id. at 146–47.
28. Id. at 146 (quoting Daubert, 509 U.S. at 595).
29. Id. at 146.
15
OCR for page 16
Reference Manual on Scientific Evidence
Justice Stevens, in his partial dissent, assumed that the plaintiff’s expert was
entitled to rely on such a methodology, which he noted is often used in risk assess-
ment, and that a district court that admits expert testimony based on a weight-of-
the-evidence methodology does not abuse its discretion.30 Justice Stevens would
have remanded the case for the court below to determine if the trial court had
abused its discretion when it excluded the plaintiff’s experts.31
C. Kumho Tire Co. v. Carmichael
Less than one year after deciding Joiner, the Supreme Court granted certiorari in
Kumho to decide if the trial judge’s gatekeeping obligation under Daubert applies
only to scientific evidence or if it extends to proffers of “technical, or other special-
ized knowledge,” the other categories of expertise recognized in Federal Rule of
Evidence 702. In addition, there was uncertainty about whether disciplines such as
economics, psychology, and other “soft” sciences were governed by this standard;
about when the four factors endorsed in Daubert as indicators of reliability had to
be applied; and how experience factors into the gatekeeping process. Although
Rule 702 specifies that an expert may be qualified through experience, the Court’s
emphasis in Daubert on “testability” suggested that an expert should not be allowed
to base a conclusion solely on experience if the conclusion can easily be tested.
In Kumho, the plaintiffs brought suit after a tire blew out on a minivan, caus-
ing an accident in which one passenger died and others were seriously injured.
The tire, which was manufactured in 1988, had been installed on the minivan
sometime before it was purchased as a used car by the plaintiffs in 1993. In their
diversity action against the tire’s maker and its distributor, the plaintiffs claimed
that the tire was defective. To support this allegation, the plaintiffs relied primarily
on deposition testimony by an expert in tire-failure analysis, who concluded on
the basis of a visual inspection of the tire that the blowout was caused by a defect
in the tire’s manufacture or design.
When the defendants moved to exclude the plaintiffs’ expert, the district
court agreed with the defendants that the Daubert gatekeeping obligation applied
not only to scientific knowledge but also to “technical analyses.”32 The district
court excluded the plaintiffs’ expert and granted summary judgment. Although
the court conceded on a rehearing that it had erred in treating the four factors dis-
cussed in Daubert as mandatory, it adhered to its original determination because the
court simply found the Daubert factors appropriate, analyzed them, and discerned
no competing criteria sufficiently strong to outweigh them.33
30. Id. at 153–54.
31. Id. at 150–51.
32. Carmichael v. Samyang Tire, Inc., 923 F. Supp. 1514, 1522 (S.D. Ala. 1996), rev’d, 131
F.3d 1433 (11th Cir. 1997), rev’d sub nom. Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999).
33. Id. at 1522, 1524.
16
OCR for page 17
The Admissibility of Expert Testimony
The Eleventh Circuit reversed the district court’s decision in Kumho, holding,
as a matter of law under a de novo standard of review, that Daubert applies only
to scientific opinions.34 The court of appeals drew a distinction between expert
testimony that relies on the application of scientific theories or principles—which
would be subject to a Daubert analysis—and testimony that is based on the expert’s
“skill- or experience-based observation.”35 The court then found that the testi-
mony proffered by plaintiff was “non-scientific” and that “the district court erred
as a matter of law by applying Daubert in this case.”36 The circuit court agreed that
the trial court has a gatekeeping obligation; its quarrel with the district court was
with that court’s assumption that Daubert’s four factors had to be applied.
All of the justices of the Supreme Court, in an opinion by Justice Breyer, held
that the trial court’s gatekeeping obligation extends to all expert testimony,37 and
unanimously rejected the Eleventh Circuit’s dichotomy between the expert who
“relies on the application of scientific principles” and the expert who relies on
“skill- or experience-based observation.”38 The Court noted that Federal Rule of
Evidence 702 “makes no relevant distinction between ‘scientific’ knowledge and
‘technical’ or ‘other specialized’ knowledge,” and “applies its reliability standard
to all . . . matters within its scope.”39 Furthermore, said the Court, “no clear line”
can be drawn between the different kinds of knowledge, and “no one denies that
an expert might draw a conclusion from a set of observations based on extensive
and specialized experience.”40
The Court also unanimously found that the court of appeals had erred when
it used a de novo standard, instead of the Joiner abuse-of-discretion standard, to
determine that Daubert’s criteria were not reasonable measures of the reliability
of the expert’s testimony.41 As in Joiner, and again over the dissent of Justice
Stevens,42 the Court then examined the record and concluded that the trial court
had not abused its discretion when it excluded the testimony of the witness.
Accordingly, it reversed the opinion of the Eleventh Circuit.
The opinion adopts a flexible approach that stresses the importance of iden-
tifying “the particular circumstances of the particular case at issue.”43 The court
must then make sure that the proffered expert will observe the same standard of
“intellectual rigor” in testifying as he or she would employ when dealing with
similar matters outside the courtroom.44
34. Carmichael v. Samyang Tire, Inc., 131 F.3d 1433, 1435 (11th Cir. 1997).
35. Id.
36. Id. at 1436 (footnotes omitted).
37. Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999).
38. Id. at 151.
39. Id. at 148.
40. Id. at 156.
41. Id. at 152.
42. Id. at 158.
43. Id. at 150.
44. Id. at 152.
17
OCR for page 18
Reference Manual on Scientific Evidence
How this extremely flexible approach of the Court is to be applied emerges in
Part III of the opinion when the Court engages in a remarkably detailed analysis
of the record that illustrates its comment in Joiner that an expert must account for
“how and why” he or she reached the challenged opinion.45
The Court illustrated the application of this standard to the facts of the case
and its deference to the district court findings as follows:
After examining the transcript in some detail, and after considering respondents’
defense of Carlson’s methodology, the District Court determined that Carlson’s
testimony was not reliable. It fell outside the range where experts might rea-
sonably differ, and where the jury must decide among the conflicting views of
different experts, even though the evidence is shaky. In our view, the doubts
that triggered the District Court’s initial inquiry here were reasonable, as was the
court’s ultimate conclusion.46
Although Kumho is the most recent pronouncement by the Supreme Court
on how to determine whether proffered testimony by an expert is admissible,
and Rule 702 of the Federal Rules of Evidence was amended in 2000 to provide
“some general standards that the trial court must use to assess the reliability and
helpfulness of proffered expert testimony,” it is still Daubert that trial courts cite
and rely on most frequently when ruling on a motion to preclude expert testi-
mony.47 Even though Daubert interprets a federal rule of evidence, and rules of
evidence are designed to operate at trial, Daubert’s greatest impact has been pre-
trial: If plaintiff’s experts can be excluded from testifying about an issue crucial to
plaintiff’s case, the litigation may end with summary judgment for the defendant.
Furthermore, although summary judgment grants are reviewed de novo by an
appellate court, there is nothing to review if plaintiff failed to submit admissible
evidence on a material issue. Consequently, only the less stringent abuse-of-
discretion standard will apply, and there will be less chance for a reversal on appeal.
D. Weisgram v. Marley
Plaintiff is entitled to only one chance to select an expert who can withstand a
Daubert motion. In a fourth Supreme Court case, Weisgram v. Marley,48 the district
court ruled for plaintiffs on a Daubert motion and the plaintiffs won a jury verdict.
On appeal, the circuit court found that, despite the abuse-of-discretion standard,
plaintiff’s experts should have been excluded and granted judgment as a matter
of law for the defendants. Plaintiffs argued that they now had the right to a new
trial at which they could introduce more expert testimony. The Supreme Court
45. Gen. Elec. Co v. Joiner, 522 U.S. 136, 144 (1997).
46. Kumho Tire Co. v. Carmichael, 526 U.S. at 153.
47. A search of federal cases on Westlaw after Kumho was decided indicates that the Daubert
decision has been cited more than twice as often as the Kumho decision.
48. 528 U.S. 440 (2000).
18
OCR for page 19
The Admissibility of Expert Testimony
granted certiorari limited to the new trial issue (it did not review the Daubert
determination) but refused to grant a new trial. Justice Ginsberg explained:
Since Daubert, moreover, parties relying on expert testimony have had notice of
the exacting standards of reliability such evidence must meet. . . . It is implau-
sible to suggest, post-Daubert, that parties will initially present less than their best
expert evidence in the expectation of a second chance should their first trial fail.49
Weisgram causes tactical problems for plaintiffs about how much to spend
for expert testimony. Should they pay for additional expensive expert testimony
even though they think the district court would rule in their favor on a Daubert
motion, or is the risk of a reversal on Daubert grounds and a consequent judgment
for the defendant too great despite the abuse-of-discretion standard? Weisgram
may indeed push plaintiffs to bring the very best expertise into litigation—a
stated goal of the trilogy, but it may also make it difficult to litigate legitimate
claims because of the cost of expert testimony. Is access to the federal courts less
important than regulating the admissibility of expert testimony? Even if plaintiffs
successfully withstand a Daubert motion, that does not guarantee they will win
were the case to be tried. But very few cases now go to trial, and an inability by
the defendant to exclude plaintiffs’ experts undoubtedly affects the willingness
of the defendant to negotiate a settlement.
II. Interpreting Daubert
Although almost 20 years have passed since Daubert was decided, a number of
basic interpretive issues remain.
A. Atomization
When there is a Daubert challenge to an expert, should the court look at all the
studies on which the expert relies for their collective effect or should the court
examine the reliability of each study independently? The issue arises with proof of
causation in toxic tort cases when plaintiff’s expert relies on studies from different
scientific disciplines, or studies within a discipline that present different strengths
and weaknesses, in concluding that defendant’s product caused plaintiff’s adverse
health effects. Courts rarely discuss this issue explicitly, but some appear to look
at each study separately and give no consideration to those studies that cannot
alone prove causation.
Although some use the language in Joiner as the basis for this slicing-and-dic-
ing approach,50 scientific inference typically requires consideration of numerous
49. 528 U.S. at 445 (internal citations omitted).
50. See discussion, supra notes 28–31 and related text.
19
OCR for page 20
Reference Manual on Scientific Evidence
findings, which, when considered alone, may not individually prove the conten-
tion.51 It appears that many of the most well-respected and prestigious scientific
bodies (such as the International Agency for Research on Cancer (IARC), the
Institute of Medicine, the National Research Council, and the National Institute
for Environmental Health Sciences) consider all the relevant available scientific
evidence, taken as a whole, to determine which conclusion or hypothesis regard-
ing a causal claim is best supported by the body of evidence. In applying the scien-
tific method, scientists do not review each scientific study individually for whether
by itself it reliably supports the causal claim being advocated or opposed. Rather,
as the Institute of Medicine and National Research Council noted, “summing,
or synthesizing, data addressing different linkages [between kinds of data] forms a
more complete causal evidence model and can provide the biological plausibility
needed to establish the association” being advocated or opposed.52 The IARC has
concluded that “[t]he final overall evaluation is a matter of scientific judgment
reflecting the weight of the evidence derived from studies in humans, studies in
experimental animals, and mechanistic and other relevant data.”53
B. Conflating Admissibility with Sufficiency
In Daubert, Justice Blackmun’s opinion explicitly acknowledges that in some cases
admissible evidence may not suffice to support a verdict in favor of plaintiffs. In
other words, it seems to recognize that the admissibility determination comes first
and is separate from the sufficiency determination. But in Joiner the Court pays
little attention to this distinction and suggests that plaintiff’s expert testimony may
be excluded if the evidence on which he seeks to rely is itself deemed insufficient.
But what difference does it make if sufficiency is conflated with admissibility?54
After all, the case’s final outcome will be the same. As Daubert recognizes, the trial
judge’s authority to decide whether the plaintiff has produced sufficient evidence
to withstand a dispositive motion under Rule 56 or 50 is indisputable; a one-step
process that considers sufficiency when adjudicating a Daubert motion is arguably
51. See e.g., Susan Haack, An Epistemologist in the Bramble-Bush: At the Supreme Court with
Mr. Joiner, 26 J. Health Pol. Pol’y & L. 217–37 (1999) (discussing the individual studies that lead to
the compelling inference of a double-helical structure of a DNA molecule, which, when considered
separately, fail to compel that inference). See also Milward v. Acuity Specialty Products Group, Inc., __
F.3d __, 2011 WL 982385, *10 639 F.3d 11, 26 (1st Cir. 2011) (reversing the district court’s exclusion
of expert testimony based on an assessment of the direct causal effect of the individual studies, finding
that the “weight of the evidence” properly supported the expert’s opinion that exposure to benzene
can cause acute promyelocytic leukemia).
52. Institute of Medicine and National Research Council, Dietary Supplements: A Framework
for Evaluating Safety 262 (2005).
53. Vincent J. Cogliano et al., The Science and Practice of Carcinogen Identification and Evaluation,
112 Envtl. Health Persp. 1272 (2004).
54. The distinction between admissibility and sufficiency is also discussed in Michael D. Green
et al., Reference Guide on Epidemiology, Section VII, in this manual.
20
OCR for page 21
The Admissibility of Expert Testimony
more efficient than a two-step process that requires the district judge to analyze
admissibility before it can turn to sufficiency.
There are, however, consequences to conflating admissibility and sufficiency.
The de novo standard of review that ordinarily applies to judgments as a matter of
law following a determination of insufficient evidence is converted into the lower
abuse-of-discretion standard that governs evidentiary rulings on admissibility, and
thereby undermines the jury trial mandate of the Seventh Amendment. Science
proceeds by cumulating and synthesizing evidence until there is enough for a new
paradigm. That does not mean that every study meets the most rigorous scientific
standards. Judgment is required in determining which inferences are appropriate,
but an approach that encourages looking at studies sequentially rather than holisti-
cally has costs that must be considered.
C. Credibility
Daubert and the expense of litigation make it difficult for courts to hew to the line
that assigns credibility issues to the jury rather than the court. One troublesome
area is conflicts of interest. To what extent should a court permit the plaintiff to
inquire into the defense expert’s relationship with the defendant? If the expert
testified at trial, information that could have skewed the expert’s testimony could
be brought to the attention of the jury through cross-examination or extrinsic
evidence. Impeachment by bias suffers from fewer constraints than other forms
of impeachment.55 But suppose the defendant seeks through a Daubert challenge
to exclude the plaintiff’s expert witness as relying on unreliable evidence to show
causation in a toxic tort action. The defendant supports its argument with testi-
mony by an academic from a highly respected institution whose research shows
that the defendant’s product is safe. Should the court permit the plaintiff to inquire
whether the expert was on the payroll of the defendant corporation, or attended
conferences paid for by the defendant, or received gifts from the defendant? What
about corporate employees ghostwriting reports about their products that are then
submitted in someone else’s name? Other ties that an expert may have to industry
have also been reported: royalties, stock ownership, working in an institution that
receives considerable funding from the defendant. These are all practices that have
been reported in the media and are practices that the plaintiff would like to ques-
tion the expert about under oath.56 A court is unlikely to allow a wide-ranging
55. See United States v. Abel, 469 U.S. 45, 50 (1984) (explaining that “proof of bias is almost
always relevant because the jury, as finder of fact and weigher of credibility, has historically been
entitled to assess all evidence which might bear on the accuracy and truth of a witness’ testimony”).
56. See, e.g., In re Welding Fume Products, 534 F. Supp. 2d 761, 764 (N.D. Ohio 2008)
(requiring all parties to the litigation to “disclose the fact of, and the amounts of, payments they made,
either directly or indirectly, to any entity (whether an individual or organization) that has authored
or published any study, article, treatise, or other text upon which any expert in this MDL litigation
relies, or has relied”).
21
OCR for page 26
Reference Manual on Scientific Evidence
Suppose, for example, that plaintiff alleges that her unborn child suffered
injuries when her room was sprayed with an insecticide. Plaintiff’s expert is pre-
pared to testify that she relied on another expert’s opinion that the insecticide can
cause harm of the sort suffered by the child and that academic studies have found
injuries when less than the amount sprayed in this case was used. But the expert
who offered this opinion reached this conclusion without considering the size of
the house, or the area treated, or how it was applied, or the amount applied to
the outside of the house. And no one had measured this substance in the mother.
Consequently, the court found that plaintiff had not provided adequate proof of
exposure.72
A recent case that illustrates the complex problems that arise with exposure
issues is Henricksen v. ConocoPhilips Co.73 In Henricksen, the plaintiff who drove a
gasoline tanker truck for 30 years alleged that his acute myelogenous leukemia
(AML) was caused by his occupational exposure to benzene, a component of gaso-
line. Although some studies show that AML, or at least some forms of AML, may
be caused by exposure to benzene, the same is not true with regard to gasoline.
The court rejected testimony by plaintiff’s experts that sought to link the exposure
to the benzene in the gasoline to plaintiff’s claim. There were numerous problems:
Did plaintiff manifest symptoms typical of AML that was chemically induced and
not idiopathic? How could one calculate how much benzene plaintiff would have
been exposed to considering how many hours he worked and how the gasoline
was delivered? How much benzene exposure is required to support the conclu-
sion that general causation has been established? Each of these issues is discussed
in considerable detail, suggesting that the studies that would logically be needed
to conclude that the alleged exposure can be linked to causation may simply not
have been done. Because the plaintiff bears the burden of proof, this means that
plaintiff’s experts often will be excluded.
IV. Forensic Science
To date, Daubert has rarely been raised in the forensic context, but this may be
about to change.74 We do not know as yet what shifts may occur in response to
the National Academies’ highly critical report on the forensic sciences.75 We do
know that the report played a role in the Supreme Court’s opinion in Melendez-
with levels of harm—plaintiff must only produce evidence from which a reasonable person could
conclude that the defendant’s emissions probably caused the plaintiff’s harms.”).
72. Junk v. Terminix Int’l. Co., 594 F. Supp. 2d 1062 (S.D. Iowa 2008).
73. 605 F. Supp. 2d 1142 (E.D. Wash. 2009).
74. These issues are discussed at greater length in Paul C. Giannelli et al., Reference Guide on
Forensic Identification Expertise, in this manual.
75. National Research Council, Strengthening Forensic Science in the United States: A Path
Forward (2009).
26
OCR for page 27
The Admissibility of Expert Testimony
Diaz v. Massachusetts76 concerning the application of the Confrontation Clause to
expert forensic testimony. But it will take some time to understand the repercus-
sions this opinion will cause in the criminal justice system.
Even aside from this constitutional development and in the absence of con-
gressional or other institutional action, the extensive coverage of the National
Academies’ report by the media and academia may bring about change. Further-
more, analysts of the more than 200 DNA exonerations to date claim that in more
than 50% of the cases, invalid, or improperly conducted, or misleadingly inter-
preted forensic science contributed to the wrongful convictions.77 The seriousness
of these mistakes is aggravated because some of the inmates were on death row.
These developments may affect judicial approaches to opinions offered by pros-
ecution experts. Also, as judges write more sharply focused opinions in civil cases,
the very different approach they use in criminal cases stands out in vivid contrast.
Supposedly, the federal rules are trans-substantive, and it is certainly arguable that
errors that bear on life and liberty should weigh more heavily than errors in civil
cases concerned primarily with money.
To date, however, few prosecution experts have been excluded as witnesses
in criminal prosecutions.78 Usually judges have allowed them to testify or, at most,
have curtailed some of the conclusions that prosecution experts sought to offer.79
However, there are a number of issues in forensic sciences that may become the
object of Daubert challenges.
A. Validity
As the discussion in Chapter 5 of the National Academies’ report recounts, foren-
sic fields vary considerably with regard to the quantity and quality of research done
to substantiate that a given technique is capable of making reliable individualized
76. 129 S. Ct. 2527, 2536 (2009).
77. The Innocence Project, available at www.innocenceproject.org.
78. See Maryland v. Rose, Case No. K06-0545 at 31 (Balt. County Cir. Ct. Oct. 19, 2007)
(excluding fingerprint evidence in a death penalty case as a “subjective, untested, unverifiable identi-
fication procedure that purports to be infallible”).
79. See, e.g., United States v. Green, 405 F. Supp. 2d 104 (D. Mass. 2005) (explaining that an
expert would be permitted to describe similarities between shell casings but prohibited from testifying
to match; Judge Gertner acknowledged that toolmark identification testimony should be excluded
under Daubert, but that every single court post-Daubert admitted the testimony); United States v.
Glynn, 578 F. Supp. 2d 567 (S.D.N.Y. 2008) (explaining that testimony linking bullet and casings
to the defendant was inadmissible under Daubert, but testimony that the evidence was “more likely
than not” from the firearm was admissible under Federal Rule of Evidence 401); United States v.
Rutherford, 104 F. Supp. 2d 1190, 1193 (D. Neb. 2000) (handwriting experts permitted to testify to
similarities between sample from defendant and document in question but not permitted to conclude
that defendant was the author). See United States v. Rutherford, 104 F. Supp. 2d 1190, 1193 (D. Neb.
2000); United States v. Hines, 55 F. Supp. 2d 530 (D. Md. 2002).
27
OCR for page 28
Reference Manual on Scientific Evidence
identifications. Non-DNA forensic techniques often turn on subjective analyses.80
But making Daubert objections in these fields requires defense counsel to under-
stand in detail how the particular technique works, as well as to be knowledgeable
about the scientific method and statistical issues.81
B. Proficiency
Non-DNA forensic techniques often rely on subjective judgments, and the profi-
ciency of the expert to make such judgments may become the focus of a Daubert
challenge. In theory, proficiency tests could determine whether well-trained
experts in those fields can reach results with low error rates. In practice, however,
there are numerous obstacles to such tests. Sophisticated proficiency tests are dif-
ficult and expensive to design. If the tests are too easy, the results will not assess the
ability of examiners to draw correct conclusions when forensic evidence presents
a difficult challenge in identifying a specific individual or source.82 Furthermore,
in many jurisdictions, forensic examiners are not independent of law enforcement
agencies and/or prosecutors’ offices and can often obtain information about a
proficiency testing program through those sources.
C. Malfunctioning Laboratories
Numerous problems have been identified in crime laboratories ranging from uncer-
tified laboratory professionals and unaccredited laboratories performing incom-
petent work to acts of deliberate fraud, such as providing falsified results from
tests that were never done.83 Although outright fraud may be rare, unintended
inaccurate results that stem from inadequate supervision, training, and record
keeping, failure to prevent contamination, and failure to follow proper statistical
procedures can have devastating effects. Evidence that a laboratory has engaged in
such practices should certainly lead to Daubert challenges for lack of reliability, but
this requires that such investigations be undertaken and the defense have access to
the results. Whether courts can be persuaded to almost automatically reject labora-
tory results in the absence of proper accreditation of laboratories and certification
80. See National Research Council, supra note 75, at 133.
81. Specific forensic science techniques are discussed in Paul C. Giannelli et al., Reference
Guide on Forensic Identification Expertise, Sections V–X, in this manual.
82. United States v. Llera Plaza, 188 F. Supp. 2d 549 (E.D. Pa. 2002) (court acknowledged
that defense raised real questions about the adequacy of proficiency tests taken by FBI fingerprint
examiners but concluded that fingerprint testimony satisfied Daubert in part because no examples were
shown of erroneous identifications by FBI examiners). An erroneous FBI identification was made in
the Brandon Mayfield case discussed in the introduction to Strengthening Forensic Science in the United
States, supra note 75, at 45–46.
83. See National Research Council, supra note 75, at 183–215 and Paul C. Giannelli et al.,
Reference Guide on Forensic Identification Expertise, Section IV, in this manual.
28
OCR for page 29
The Admissibility of Expert Testimony
of forensic practitioners remains to be seen. Laboratory techniques, such as drug
analyses, that do not suffer from the same uncertainties regarding validity as the
forensic identification techniques can, of course, also produce erroneous results if
the laboratory is failing to follow proper procedures.
D. Interpretation
Forensic techniques that rest on subjective judgments are susceptible to cognitive
biases.84 We have seen instances of contextual bias, but as yet there has been little
research on contextual or other types of cognitive bias. We do not yet know
whether courts will consider this type of evidence when expertise is challenged.
E. Testimony
Defense counsel may of course object to testimony that a prosecution expert seeks
to give. When the prosecution relies on a subjective identification technique,
lawyers for the defense should attempt to clarify what “match” means if the expert
uses this terminology and to explain to the jury that studies to date do not per-
mit conclusions about individualization. To do this, the defense may have to call
its own experts and ask for jury instructions. Defense counsel must also remain
alert and object to prosecution testimony in which the witness claims to know
probabilities—that have not been established in a particular field—on the basis of
extensive personal experience. Objections also should be raised to testimony about
zero error rates. The defense must also remember that the Daubert opinion itself
recognized that testimony can be excluded under Federal Rule of Evidence 403
if its prejudicial effect substantially outweighs its probative value.
F. Assistance for the Defense and Judges
Perhaps the most troubling aspect of trying to apply Daubert to forensic evidence is
that very few defense counsel are equipped to take on this challenge. Such counsel
lack the training and resources to educate judges on these complex issues. Judges
in the state criminal justice system that handle the great majority of criminal cases
often have overloaded dockets and little or no assistance. Whether a defendant in a
particular case is constitutionally entitled to expert assistance is a complicated issue
that defense counsel needs to explore.85 Possibly the best chance for the defense to
get meaningful help that also would assist the court is to get pro bono assistance
84. National Research Council, supra note 75, at 184–185.
85. See Ake v. Oklahoma, 470 U.S. 68 (1985) (recognizing indigent’s right to psychiatric expert
assistance in a capital case in which defendant raised insanity defense). Jurisdictions differ widely in
how they interpret Ake.
29
OCR for page 30
Reference Manual on Scientific Evidence
from other counsel who are knowledgeable about Daubert and have a sophisticated
understanding of statistical reasoning. Lawyers who have handled complex issues
about causation may be able to transfer their expertise to other difficult issues
relating to expert testimony.86 Judges might also consider asking for amicus briefs
from appropriate organizations or governmental units.
G. Confrontation Clause
The majority in Melendez-Diaz v. Massachusetts, in an opinion by Justice Scalia over
a strong dissent by Justice Kennedy, held that the defendant has a constitutional
right to demand that a forensic analyst whose conclusions the prosecution wishes
to introduce into evidence must be produced in court for cross-examination. In
a drug case, for example, the prosecution may not simply introduce a report or
an affidavit from the analyst if the defendant demands production of the analyst
for cross-examination. When the analyst is produced, this will gave the defense
the opportunity through cross-examination to raise questions about fraud, incom-
petence, and carelessness and to ask questions about laboratory procedures and
other issues discussed in the National Research Council report. Effective cross-
examination will demand of defense counsel the same type of expertise needed
to succeed on Daubert challenges. Numerous unanswered questions about the
operation of Melendez-Diaz will have to be litigated. It remains to be seen how
often, if at all, defense counsel will take advantage of the Confrontation Clause
or whether they will waive the defendant’s right to confront expert witnesses.87
V. Procedural Context
Apart from their effect on admissibility of expert testimony, Daubert and its sub-
sequent interpretations have also affected the broader context in which such cases
are litigated and have altered the role of testifying experts in the pretrial stages of
litigation.
A. Class Certification Proceedings
One question that arises with increasing frequency is whether and how Daubert is
to be applied at class certification proceedings. The problem arises because of the
commonality and predominance requirements in Rule 23(a) of the Federal Rules
86. Cf. Kitzmiller v. Dover Area School Dist., 400 F. Supp. 2d 707 (M.D. Pa. 2005) (attorneys
who specialized in defense product liability litigation and had expertise about the nature of science
participated in case objecting to teaching intelligent design in public schools).
87. Both defendants and prosecutors face concerns about the resources required to fully imple-
ment such protections. See National Research Council, supra note 75, at 187.
30
OCR for page 31
The Admissibility of Expert Testimony
of Civil Procedure and has emerged with regard to a wide variety of substantive
claims that plaintiffs seek to bring as a class action. For example, in Sanneman v.
Chrysler Corp.,88 plaintiff sought class certification of a common-law fraud action
and a breach-of-warranty action, the gist of which was “that Chrysler had fraudu-
lently concealed a paint defect in many of the vehicles it manufactured beginning
on or about 1990.”89 Plaintiff’s expert testified at the class certification hearing
that the paint problem is always caused by ultraviolet rays, but acknowledged
“that other causes may contribute to or exacerbate the problem.”90 After oral
argument, the court concluded that plaintiff’s expert’s testimony satisfied Daubert,
but because ultraviolet rays are not always the only cause of problems with paint,
proof of damages would probably have to be made vehicle by vehicle. The motion
for class certification was therefore denied. Daubert challenges have been raised to
class certification in numerous other cases.91
As of this writing, there is a decided trend toward rejecting class certifica-
tion on the ground that plaintiff’s proffered expert testimony does not satisfy the
Rule 23(a) requirements, although the circuits are not unanimous in how rigor-
ous the examination of expert proof needs to be. Must the expert testimony be
subjected to the same rigorous scrutiny to determine whether it is relevant and
reliable as when the issue is admissibility at trial, or is a less searching analysis
appropriate at the certification stage? In other words, should the trial judge con-
duct a Daubert hearing and analysis identical to that undertaken when a defendant
seeks to preclude a plaintiff’s witness from testifying at trial? Not only “should”
the trial judge conduct a Daubert hearing, but, as the Seventh Circuit has ruled in
American Honda, the trial judge “must” do so. If a full Daubert hearing is required
in every class certification case, what has happened to the broad and case-familiar
discretion that a trial judge is supposed to exercise?”
The trial judge in Rhodes v. E.I. du Pont de Nemours & Co.92 concluded that
the expert opinions offered in support of class certification should be subjected
to a full-scale Daubert analysis, including a Daubert hearing. The judge explained
88. 191 F.R.D. 441 (E.D. Pa. 2000).
89. Id. at 443.
90. Id. at 451.
91. See, e.g., Blades v. Monsanto Co., 400 F.3d 562 (8th Cir. 2005) (antitrust price-fixing con-
spiracy); Rhodes v. E.I. du Pont de Nemours & Co., 2008 WL 2400944 (S.D. W. Va. June 11, 2008)
(medical monitoring claim in toxic tort action); Gutierrez v. Johnson & Johnson, 2006 WL 3246605
(D.N.J. Nov. 6, 2006) (employment discrimination); Nichols v. SmithKline Beecham Corp., 2003 WL
302352 (E.D. Pa. Jan. 29, 2003) (violation of Sherman Antitrust Act); In re St. Jude Med., Inc., 2003
WL 1589527 (D. Minn. Mar. 27, 2003) (product liability action); Bacon v. Honda of Am. Mfg Inc.,
205 F.R.D. 466 (S.D. Ohio 2001) (same); Midwestern Mach v. Northwest Airlines, Inc., 211 F.R.D.
562 (D. Minn. 2001) (violation of Clayton Act); In re Polypropylene Carpet, 996 F. Supp. 18 (N.D.
Ga. 1997) (same); In re Monosodium Glutamate, 205 F.R.D. 229 (D. Minn. 2001).
92. 2008 WL 2400944 (S.D. W. Va. June 11, 2008). See also American Honda Motor Co. v.
Allen, 600 F.3d 813, 816 (7th Cir. 2010) (district court must perform a full Daubert analysis before
certifying a class action where the expert’s report or testimony is critical to class certification).
31
OCR for page 32
Reference Manual on Scientific Evidence
that decisions that see a more limited role for Daubert in class certification hearings
stem in part from misinterpreting the Supreme Court’s opinion in Eisen v. Carlisle
& Jacquelin.93 In Eisen, which predated Daubert by 19 years, the Court instructed
district courts to refrain from conducting “a preliminary inquiry into the merits
of a proposed class action” when they consider certification.94 At this time, only
the Ninth Circuit forbids the lower courts from examining evidence that relates to
the merits and from requiring a rigorous examination of the expert testimony and
Rule 23(a) requirements.95 The Rhodes case deplored this approach because the
overwhelming majority of class actions settle and therefore allowing the action to
proceed as a class action “might invite plaintiffs to seek class status for settlement
purposes.” On the other hand, knocking out the possibility of class certification
early in the proceedings affects the possibility of settling cases in which liability is
debatable. A possible compromise is partial certification that would allow a com-
mon issue to be established at a class trial, leaving individual issues for separate
proceedings.
B. Discovery
1. Amended discovery rules
Rule 26 of the Federal Rules of Civil Procedure—the core rule on civil discovery—
was amended in 1993 more or less contemporaneously with Daubert to allow judges
to exert greater control of expert testimony. Those amendments required experts
retained or specially employed to provide expert testimony, or whose duties as the
party’s employee regularly involve giving expert testimony, to furnish an extensive
report prior to his or her deposition.96 These reports were required to indicate
93. 417 U.S. 156 (1974).
94. Id. at 177–78.
95. See Dukes v. Wal-Mart, Inc., 474 F.3d 1214 (9th Cir. 2007). The Supreme Court declined
an opportunity to address the role of Daubert in class certification when it granted certiorari in Dukes,
even though the issue was raised in some of the petitions. The Court subsequently granted a petition
for certiorari in Erica P. John Fund Inc. v. Halliburton Co. (U.S. Jan. 7, 2011) (No. 09-1403), which
raises related questions regarding the extent to which the district court may consider the merits of the
underlying litigation and require that loss causation be demonstrated by a preponderance of admissible
evidence at the class certification stage under Federal Rule of Civil Procedure 23. Other courts accord
Daubert a limited role, such as requiring the trial judge to determine only that the expert testimony is
“not fatally flawed.” See Fogarazzo v. Lehman Bros., Inc., 2005 WL 361205 (S.D.N.Y. Feb. 16, 2005).
96. Fed R. Civ. P. 26(a)(2)(B), as amended December 1, 2010, made substantial changes to the
1993 amendments. The 1993 amendments also recognized a second category of testifying experts who
were not retained or specially employed in anticipation of litigation, such as treating physicians, who
were not required to provide reports. But see 3M v. Signtech USA, 177 F.R.D. 459 (D. Minn. 1998)
(requiring report from employee experts who do not regularly provide expert testimony because it
eliminates surprise and is consistent with the spirit of Rule 26(a)(2)(B)). Under the 2010 amendments
the attorney must submit a report indicating the subject matter and the facts and opinions to which an
unretained testifying expert is expected to testify. Fed. R. Civ. P. 26(a)(2)(C) (amended Dec. 1, 2010).
32
OCR for page 33
The Admissibility of Expert Testimony
“the data or other information considered by the expert witness in forming the opin-
ions” (emphasis added). Many, although not all, courts construed this language as
opening the door to discovery of anything conveyed by counsel to the expert.97
Courts taking this approach found that all communications between counsel and
experts were discoverable even if the communication was opinion work product.
In other words, these courts found that the protection for opinion work product in
Rule 26(b)(3) was trumped by the disclosure provisions in Rule 26(a)(2)(B). These
courts also required disclosure of all the expert’s draft reports and notes.
Trigon Ins. Co. v. United States,98 went a step further. It held that drafts
prepared with the assistance of consultants who would not testify, as well as all
communications between the consultants and the experts, including e-mails,
were discoverable. In Trigon, many of these materials had been destroyed. The
court ordered the defendant to hire an outside technology consultant to retrieve
as much of these data as possible, allowed adverse inferences to be drawn against
the defendant, and awarded more than $179,000 in fees and costs to plaintiff.99
Those who favor the free discovery of communications between counsel and
experts and draft reports justified these results as shedding light on whether the
expert’s opinions are his or her own or those of counsel. Critics of this approach
found it costly and time-consuming and point out that lawyers have developed
strategies to overcome transparency, such as retaining two sets of experts—one to
consult and the other to testify—which makes discovery even more expensive.
After a series of public hearings the Advisory Committee on Civil Rules
determined that the disclosure rules increased the cost of litigation with no offset-
ting advantage to the conduct of litigation. The report of the Advisory Committee
noted that such an extensive inquiry into expert communications with attorneys
did not lead to better testing of expert opinions “because attorneys and expert
witnesses go to great lengths to forestall discovery.”100
Under amended rules that became effective in December 2010, disclosure is
limited to “the facts or data” considered by the expert, and does not extend to
“other information.” Draft reports are no longer discoverable, and communica-
tions between counsel and an expert are protected from discovery unless the
communications: (1) relate to compensation for the expert’s study or testimony;
97. See Karn v. Ingersoll Rand, 168 F.R.D. 633 (N.D. Ind. 1996) (requiring disclosure of all
documents reviewed by experts in forming their opinions); Reg’l Airport Auth. v. LFG, LLC, 460
F.3d 697, 716 (6th Cir. 2006) (“other information” interpreted to include all communications by
counsel to expert).
98. 204 F.R.D. 277 (E.D. Va. 2002).
99. Id. See also Semtech Corp. v. Royal Ins. Co., 2007 WL 5462339 (C.D. Cal. Oct. 24, 2007)
(explaining that preclusion of expert from testifying for failure to disclose drafts and failing to disclose
input of counsel at hearing made it impossible to discern the basis for his opinion).
100. Report of the Civil Rules Advisory Committee, from Honorable Mark R. Kravitz, Chair,
Advisory Committee on Federal Rules of Civil Procedure, to Honorable Lee H. Rosenthal, Chair,
Standing Committee on Rules of Practice and Procedure (May 8, 2008), available at http://www.
uscourts.gov/uscourts/RulesAndPolicies/rules/Reports/CV05-2009.pdf.
33
OCR for page 34
Reference Manual on Scientific Evidence
(2) identify facts or data provided by counsel and considered by the expert; or
(3) identify assumptions furnished by counsel that the expert relied upon in form-
ing opinions. Testifying experts who were not required to provide a report under
the previous rules—such as treating physicians—are now required to provide a
summary of the facts or opinions to which the witness expects to testify. While this
requirement relating to experts not required to file a report would provide more
disclosure than under the 1993 amendments, the main thrust of the 2010 amend-
ments is to narrow expert discovery with an eye toward minimizing expense and
focusing attention on the expert’s opinion.
Nothing in the amendments precludes asking an expert at a deposition to
explain the bases or foundations for his or her opinions or asking whether the
expert considered other possible approaches, but inquiries into counsel’s input
would be severely curtailed. Aside from communications with counsel relating
to compensation, or inquiring into “facts or data” provided by counsel that the
expert considered, the expert may also be asked if counsel furnished him or her
with assumptions on which he or she relied. Now that the amended rules have
become effective, it remains to be seen how broadly courts and magistrates will
interpret the “assumptions” provision. Are there instances in which it will be
inferred that counsel was seeking to have the expert make an assumption although
this was never explicitly stated? Those who think more transparency is desirable
in dealing with expert testimony will certainly push to expand this category.
Whether these amendments if adopted can constrain the gamesmanship that sur-
rounds expert testimony remains to be seen.
2. E-discovery
Also uncertain is whether experts will be needed to determine the proper scope
of e-discovery. Rule 26(b)(2)(B) provides the following:
A party need not provide discovery of electronically stored information from
sources that the party identifies as not reasonably accessible because of undue
burden or cost.
The burden is on the party from whom discovery is sought to show this
undue burden or cost, but the court may nevertheless order discovery if the
requesting party can show good cause.
May the requesting party making a motion to compel proffer expert testi-
mony to show that the requested information would have been readily accessible
if the party with the information had used a different search methodology? Recent
opinions by a magistrate judge so suggest.101 Magistrate Judge John Facciola notes
that “[w]hether search terms or ‘keywords’ will yield the information sought is a
complicated question involving the interplay, at least, of the sciences of computer
101. See e.g. United States v. O’Keefe, 537 F. Supp. 2d 14 (D.D.C. 2008); Equity Analytics,
LLC v. Lunden, 248 F.R.D. 331 (D.D.C. 2008).
34
OCR for page 35
The Admissibility of Expert Testimony
technology, statistics and linguistics. . . . This topic is clearly beyond the ken of a
layman and requires that any conclusion be based on evidence that, for example,
meets the criteria of Rule 702 of the Federal Rules of Evidence.”102
Superimposing Daubert hearings on top of e-discovery proceedings will make
an already costly procedure even more costly, one of the consequences that
Rule 26(b)(2)(B) seeks to avoid. On the other hand, a search that would not lead
to the information sought defeats the objectives of discovery. A helpful opinion
on how these factors should be balanced that examines the issues a court must
consider can be found in Victor Shirley, Inc. v. Creative Pipe, Inc.,103 which also
contains a very brief overview of the various techniques for conducting searches of
electronically stored information. A court may well require technical assistance in
dealing with these issues. In some instances, a court-appointed expert or a special
master appointed pursuant to Rule 53 of the Federal Rules of Civil Procedure
might be more desirable than a full-fledged Daubert battle among experts, particu-
larly if one of the parties has far fewer resources than its opponent.
C. Daubert Hearings
When a Daubert issue arises, the trial court has discretion about how to proceed.104
It need not grant an evidentiary hearing and has leeway to decide when and how
issues about the admissibility of expert testimony should be determined. The bur-
den is on the parties to persuade the court that a particular procedure is needed.105
The generally unfettered power of the trial judge to make choices emerges
clearly if we look at United States v. Nacchio,106 a criminal case. The defendant
claimed that the trial judge erred in granting the government’s Daubert motion to
exclude his expert in the middle of the trial without an evidentiary hearing, lead-
ing to his conviction. On appeal, a divided panel of the Tenth Circuit reversed
on the ground that the expert testimony had been improperly excluded and
remanded for a new trial. After a rehearing, the conviction was reinstated in a 5-4
opinion. The majority rejected the defense’s central argument that the court had
to take into account that this was a criminal case; the majority saw this purely as a
Daubert issue and found that the burden of satisfying Daubert and convincing the
trial judge to hold a hearing rested solely on the defendant. Although there may
be some cases in which a reviewing court would find that the trial court abused
its discretion in the procedures it used in handling a Daubert motion,107 this has
102. See Equity Analytics, 248 F.R.D. at 333.
103. 250 F.R.D. 251 (D. Md. 2008).
104. Kumho Tire Co. v. Carmichael, 526 U.S. at 137, 150 (1999).
105. For example, in the government’s RICO tobacco case, all Daubert issues were decided on
the papers without any testimony being presented. United States v. Phillip Morris Inc., 2002 WL
34233441, at *1 (D.D.C. Sept. 30, 2002).
106. 555 F.3d 1234 (10th Cir. 2009).
107. See Padillas v. Stork-Gamco, Inc., 186 F.3d 412 (3d Cir. 1999).
35
OCR for page 36
Reference Manual on Scientific Evidence
become more and more unlikely in civil cases as Daubert rulings have accumulated
and courts increasingly expect litigators to understand their obligations.
VI. Conclusion
The Daubert trilogy has dramatically changed the legal landscape with regard to
expert witness testimony. The Supreme Court attempted in Daubert to articulate
basic principles to guide trial judges in making decisions about the admissibility
of complex scientific and technological expert testimony. Unfortunately, the
Daubert trilogy has, in actuality, spawned a huge, and expensive, new subject of
litigation and have left many procedural and substantive questions unanswered.
Moreover, there are serious concerns about whether the guidelines enunciated by
the Court have been interpreted by lower courts to limit, rather than respect, the
discretion of trial judges to manage their complex cases, whether the guidelines
conflict with the preference for admissibility contained in both the Federal Rules
of Evidence and Daubert itself, and whether the guidelines have resulted in trial
judges encroaching on the province of the jury to decide highly contested factual
issues and to judge the overall credibility of expert witnesses and their scientific
theories. Perhaps most disturbingly, there are serious concerns on the part of
many scientists as to whether the courts are, as Daubert prescribed, making admis-
sibility decisions—decisions that may well determine the ultimate outcome of a
case—which are in fact “ground[ed] in the methods and procedures of science.”108
108. Daubert v. Merrill Dow Pharms., 509 U.S. at 579, 590 (1993).
36
