387 F.3d 1244 (11th Cir. 2004)
That Rule 702 requires that an opinion like Tressel’s have scientific foundations. The district court did not, however, find Tressel’s opinion unreliable because it had no grounding in scientific studies; it found the opinion unreliable because Frazier, who had the burden of proof, offered no evidence—experience-based or otherwise—on the factual issue the court correctly identified as central to the reliability of the opinion. To ask whether there are studies validating part of the testimony of a skill- or experience-based expert is not improperly to require that the testimony rest on scientific foundations or that the expert have scientific expertise. See Kumho Tire, 526 U.S. at 157, 119 S. Ct. at 1178 (“Nor, despite the prevalence of tire testing, does anyone refer to any articles or papers that validate Carlson’s approach.”). When the expert’s experiences have not alone been shown to be capable of providing a sufficient foundation for a particular opinion, corroboration from somewhere—whether in the opinions of other experience-based witnesses or in published, scientific studies—is necessary to establish the opinion’s reliability.
The district court made an implicit finding that Tressel had not sufficiently established how his experience led him to the opinion he offered. It then went on to require that, in the absence of such evidence, Frazier show that the opinion had some support in scientific literature. Requiring that the proponent of an expert opinion provide some basis for a determination that the opinion is reliable is never an abuse of discretion.
In summary, the model for reviewing a trial court’s finding as to the reliability of an expert opinion requires that we uphold the finding unless the court abused its discretion in reaching it—that is, unless the court misapplied the law or based its finding on a clearly erroneous finding as to one or more circumstantial facts crucial to a finding of reliability. Keeping these points in mind, I think it clear that the district court did not abuse its discretion in arriving at its findings that Tressel’s opinions—that “there is no forensic evidence to substantiate the claim of rape in this case” and that if the victim’s claim of rape were true, “it would be expected that some transfer of either hairs or seminal fluid would [have] occur[red]”—were unreliable. Frazier simply failed to establish by a preponderance of the evidence the circumstantial facts that the court, in the exercise of its discretion, identified as crucial and highly relevant indicia of reliability. Because the district court did not abuse its discretion in the manner in which it resolved the reliability issues, and because the court’s findings as to the opinions’ reliability were not clearly erroneous, the court was bound to exclude them. Indeed, the court would have abused its discretion had it permitted the jury to hear them.
I concur in the majority opinion and find exceedingly useful its parsing of the methodology for admitting expert testimony that is based on experience. As the dissent accurately notes, the requirements of qualification and reliability are “often blurred in the case of experience-based expert testimony.” Birch Dissent at 111. That is precisely what the majority now clarifies and will not permit. The reliability prong is not to be “subsumed” by the qualification prong – “the reliability criterion remains a discrete, independent, and important requirement for admissibility.” Majority Op. at 33.
While experience may be sufficient to qualify a person as an expert, the ipse dixit of an expert in a given field is simply not enough to establish the reliability of a particular opinion. Id. The majority makes clear that where a witness relies solely or primarily on experience, then the witness must explain how that experience leads to the conclusion reached, why that experience is a sufficient basis for the opinion, and how that experience is reliably applied to the facts. The trial court’s gatekeeping function requires more than simply ‘taking the expert’s word for it.’
I agree that the district court properly excluded Tressel’s testimony because he failed to establish how his experience led to the specific conclusion that “it would be expected that some transfer of either hairs or seminal fluid would occur.” R5 at 24, Ex. 2 at 2. Indeed, the only support Tressel offered to validate his claim was that in one rape case he worked on he “identified head hair and pubic hair” of a serial rapist on four victims. R5 at 37-38.2 Had the government’s expert witnesses similarly failed to establish how their experience led to their conclusions, the court would have been compelled to exclude their testimony as well.3 However, as the majority points out, the government witnesses provided specific and detailed quantitative bases for their opinions. Thus, the district court acted within its discretion.
For the reasons that follow, I respectfully dissent. This is the classic case that law students study to understand the adage “hard facts make bad law.” Those hard facts (the majority calls it a “sad case” and a “crime of unspeakable brutality”) have caused the trial court and a majority of this court to elevate an evidentiary rule, improperly administered, over a criminal defendant's basic right to “present his own witnesses to establish a defense. This right is a fundamental element of due process of law.” Washington v. Texas, 388 U.S. 14, 19, 87 S. Ct. 1920, 1923 (1967); Chambers v. Mississippi, 410 U.S. 284, 302, 93 S. Ct. 1038, 1049 (1973) (“Few rights are more fundamental than that of an accused to present witnesses in his own defense.”). As demonstrated below, the exclusion of the defense's expert “gutted” its only viable defense. See, infra, notes 6 & 10. And, while the trial court is indeed vested with broad discretion in ruling upon the relevancy and admissibility of evidence, we have appropriately, until this case, held that “[s]uch discretion does not, however, extend to the exclusion of crucial relevant evidence necessary to establish a valid defense.” United States v. Kelly, 888 F.2d 732, 743 (11th Cir. 1989).
What is particularly disturbing is that the trial court allowed the government, over objection, to use two FBI laboratory technicians who were called as fact witnesses in the government's case-in-chief, on rebuttal to testify as to the import of a lack of forensic evidence found at the crime scene without requiring any support for their testimony of a statistical or scientific nature. The presence of lack of such forensic evidence and its import was precisely the testimony the defense expert witness was prohibited from providing. See, infra, notes 7 & 22. What was good for the government gander essentially cooked the defense's goose in this case.
The trial court's ruling in this case was an abuse of discretion for two principal reasons: (a) the district court committed a Daubert4 error, which involved two parts: (1) requiring scientific evidence for the defense's experience-based expert to be reliable while (2) not similarly requiring the Government's experience-based experts to have a scientific basis for their testimony; and (b) the district court's Daubert error essentially deprived Frazier of the opportunity to present a meaningful defense. I address each error in turn.
Before trial, Frazier gave notice to the Government that he intended to offer the testimony of Robert Tressel, a forensic investigator and former police officer, as an expert under Federal Rule of Evidence 702. Rule 702 “assign[s] to the trial judge the task of ensuring that an expert's testimony both rests on a reliable foundation and is relevant to the task at hand.” Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 113 S. Ct. 2786 (1993). Accordingly, the Government made a motion in limine to exclude Tressel's testimony under Daubert, and the district court accordingly held a hearing on the motion. During the Daubert hearing, it became clear that Tressel's expertise was based on his experience,5 which also was informed by scientific studies6: for ten years, Tressel worked as an investigator in Cobb County's unit on Crimes Against Persons, a unit which investigates homicides, rapes, other sexual assaults, and armed robberies. R5 at 5-6. Tressel estimated that he worked on as many as 250 sexual assault cases during his tenure. Id. at 9. In addition, Tressel spent thirteen years as chief investigator in the Cobb County Medical Examiner's Office, id. at 10, and currently owns and operates a private forensic investigation office. Def. Ex. 1. Based on Tressel's background, the district court deemed him “a very qualified criminal investigator.” R5 at 66.
Despite Tressel's qualifications as an expert, the district court decided to tightly circumscribe the limits of Tressel's proposed testimony on the ground that Tressel, as an experience-based expert, needed some scientific data or study on which to base his conclusions in order for them to be reliable7—even though the Government admitted during the Daubert hearing that such scientific evidence existed.8 The district court ruled that Tressel would be allowed to testify regarding the standard procedures in investigating the site of an alleged sexual assault and to testify that no hair or fluid matching Frazier was found. Tressel could testify, for example, that “[t]he forensic evidence most commonly found during the analysis of rape investigation is the transfer of hairs.” R5 at 24, Ex. 2 at 2. Tressel was forbidden, however, from testifying to two key propositions: (1) “Based on my review of the available documents, it is my professional opinion that there is no forensic evidence to substantiate the claim of rape in this case,” and (2) “With the amount of sexual activity described in the search warrant affidavit, it would be expected that some transfer of either hairs or seminal fluid would occur in this case.” R5 at 24, Ex. 2 at 2, 3. Both the defense and the trial judge recognized that excluding this key testimony left no further use for Tressel as a witness.9 R5 at 65-66. As a result, the defense was left to elicit the lack of forensic evidence matching Frazier from two FBI laboratory technicians—Agent Karen Lanning and Agent Anthony Onorato—who examined the evidence discovered at the crime scene after a meticulously careful collection process that no one disputed. See, e.g., R5 at 24, Ex. 2 at 2; id. at 67.
On rebuttal, however, the district court's initial Daubert error was compounded when the Government was allowed to use these same FBI laboratory technicians—used by the government as fact witnesses—to testify as experts. The Government offered the FBI agents as experience-based experts who would be asked to testify to the import of the lack of forensic evidence—the same “leap” that Tressel was not allowed to make. The defense objected, arguing that the prosecution had failed to communicate its intention to call expert witnesses, violating the notice provisions of Federal Rule of Evidence 16.10 The district court, though agreeing with the defense that the Government should have been more forthcoming with its witnesses, ultimately overruled the defense's objection, reasoning that Rule 16 only requires notice when the prosecution calls an expert during its case in chief.11 Unlike Tressel, the court permitted the technicians to testify as experts regarding “the import of the fact that there was nothing found.” R9-363. Not surprisingly, both agents testified that the lack of forensic evidence matching Frazier did not necessarily lead to the conclusion that no sexual contact had occurred. R9-371, 387.
Allowing the FBI agents to testify as to the import of finding no forensic evidence, while not allowing Tressel to do the same, essentially eviscerated Frazier's principal and only practical defense—questioning the credibility of the victim to show that if the rape did not occur, neither did the kidnapping.12 The district court even admitted as much.13 Needless to say, the Government, in its closing statement, stressed the importance of the testimony of Lanning and Onorato that the lack of forensic evidence did not mean that the rape—and, hence, the kidnapping—did not occur. The Government also mentioned the scientific “studies” that it required of Tressel but not of its own experts.14 The defense, on the other hand, without any experts to quote or studies on which to rely, could only make the bald argument that the lack of forensic evidence did not support the victim's account of the events.15
Frazier appealed, arguing that the district court abused its discretion when it limited Tressel's testimony under the guise of Daubert, thereby eviscerating his only viable defense.
In this section, I will (a) state the proper standard of review, (b) discuss the district court's erroneous Daubert rulings, and (c) discuss the effect of this ruling on Frazier's ability to present a meaningful defense.
We review a district court's exclusion of expert testimony under the federal rules of evidence for an abuse of discretion. United States v. Paul, 175 F.3d 906, 909 (11th Cir. 1999). As for the district court's interpretation of Federal Rule of Evidence 702, our review is plenary. Id. No error regarding the admission or exclusion of evidence is reversible “unless a substantial right of the party is affected.” Fed. R. Evid. 103(a).
Rule 702 of the Federal Rules of Evidence allows “a witness qualified as an expert by knowledge, skill, experience, training, or education” to testify “in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case,” provided that the “scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue.” In Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 113 S. Ct. 2786 (1993), the Supreme Court “assign[ed] to the trial judge the task of ensuring that an expert’s testimony both rests on a reliable foundation and is relevant to the task at hand.” Id. at 597, 113 S. Ct. at 2799.
Faced with a proffer of expert scientific testimony, then, the trial judge must determine at the outset, pursuant to Rule 104(a), whether the expert is proposing to testify to (1) scientific knowledge that (2) will assist the trier of fact to understand or determine a fact in issue. This entails a preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue.
Id. at 592, 113 S. Ct. at 2796 (footnotes omitted). Thus, for proffered expert testimony to be admissible, a court must determine that:
(1) the expert is qualified to testify competently regarding the matters he intends to address; (2) the methodology by which the expert reaches his conclusions is sufficiently reliable as determined by the sort of inquiry mandated in Daubert; and (3) the testimony assists the trier of fact, through the application of scientific, technical, or specialized expertise, to understand the evidence or to determine a fact in issue.
City of Tuscaloosa v. Harcros Chem., Inc., 158 F.3d 548, 562 (11th Cir. 1998).
But while “[t]he judge’s role is to keep unreliable and irrelevant information from the jury,” it “is not intended to supplant the adversary system or the role of the jury.” Allison v. McGhan Med. Corp., 184 F.3d 1300, 1311-12 (11th Cir. 1999). The admissibility standard is a liberal one, United States v. Hankey, 203 F.3d 1160, 1168 (9th Cir. 2000), and “[a] review of the caselaw after Daubert shows that the rejection of expert testimony is the exception rather than the rule.” Fed. R. Evid. 702 advisory committee notes, 2000 amends. (emphasis mine).
Courts have found that an abuse of discretion occurs when under Daubert the admissibility bar is too high. . . . “Trial judges must exercise sound discretion as gatekeepers of expert testimony under Daubert. . . . [We must not] elevate them to the role of St. Peter at the gates of heaven, performing a searching inquiry into the depth of an expert witness’s soul—separating the saved from the damned.”
Allison, 184 F.3d at 1321 (citation omitted) (quoting McCullock v. H.B. Fuller Co., 61 F.3d 1038, 1045 (2d Cir. 1995)).
Because the district court forbade Tressel from testifying to two key propositions, I address each proposition in turn and then discuss how the district court's ruling was incorrectly and inconsistently applied.
The district court would not allow Tressel to draw any inferences that the lack of forensic evidence did not substantiate the victim's claim of rape because it would invade the jury's province and usurp its role in deciding the penultimate issue of whether rape actually occurred. However, “it is part of the normal role of the expert not merely to describe patterns of conduct in the abstract, but to connect actions in a specific case to those patterns—sometimes even to the point of testifying that the defendant was [or was not] involved in criminal conduct.” United States v. Boney, 977 F.2d 624, 629 (D.C. Cir. 1992). “Rule 702 does not bar an expert from drawing conclusions in a specific case . . . [and] does not require that any inferences from the facts in the specific case be left to the jury.” Id. Thus, experts may “take the further step of suggesting the inference which should be drawn from applying the specialized knowledge to the facts.” Fed. R. Evid. 702 advisory committee notes, 1972 Proposed Rules. This is true even if the testimony “merely assist[s] the jury in interpreting the significance of the evidence,” United States v. Brown, 7 F.3d 648, 654 (7th Cir. 1993), draws on “common sense,” United States v. Glover, 265 F.3d 337, 345 (6th Cir. 2001), or, while helpful, is nonetheless “obvious,” United States v. Sellers, 566 F.2d 884, 886 (4th Cir. 1977). Indeed, “whether the specific expert testimony focuses upon specialized observations, the specialized translation of those observations into theory, a specialized theory itself, or the application of such a theory in a particular case, the expert’s testimony often will rest ‘upon an experience confessedly foreign in kind to [the jury’s] own.’” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 149, 119 S. Ct. 1167, 1174 (1999) (citation omitted) (emphasis mine).
In Brown, for instance, the defendant had been convicted of possession with intent to distribute cocaine base. 7 F.3d at 649. On appeal, “the issue was whether [he] possessed the twenty-five rocks of crack cocaine for distribution or for personal use.” Id. at 652. The government’s expert identified certain indices that are commonly associated with drug dealers. “He also described the typical paraphernalia associated with street-level crack distributors and compared that with the paraphernalia and behavior patterns usually associated with those possessing crack only for personal use.” Id. at 650. From this information, the expert concluded that the crack cocaine seized from the defendant was not intended for personal consumption, but for distribution. Id. The defendant objected, arguing that the jury could draw its own inferences from the habits and practices testimony of the expert. Id. at 652. The Seventh Circuit affirmed the district court’s refusal to exclude the testimony on the ultimate issue, reasoning that “the average juror might be unable to determine whether the absence of certain drug paraphernalia typically associated with crack cocaine is significant.” Id. (emphasis mine); see also Erickson v. Baxter Healthcare, Inc., 131 F. Supp. 2d 995, 1001 (N.D. Ill. 2001) (permitting medical expert to testify that information contained in the plaintiff’s medical records did not support one of her allegations).
In the same way, Tressel’s conclusion in this case—that the absence of any forensic evidence did not substantiate the claim of rape—would have helped the jury to understand the significance of the negative implication to be drawn; what the prosecution even referred to as the “import” of the lack of evidence. R9 at 363. Its exclusion by the district court was therefore an abuse of its discretion. Tressel’s proffered testimony did not state a legal conclusion as to Frazier’s guilt or innocence, and it did not “tell the jury what result to reach.” Montgomery v. Aetna Cas. & Sur. Co., 898 F.2d 1537, 1541 (11th Cir.1990). His analysis was clear and was supported by undisputed factual findings as to the evidence retrieved from the alleged crime scene. No mere “oath-helper,” Hanson v. Waller, 888 F.2d 806, 811 n.2 (11th Cir. 1989), Tressel’s testimony would have assisted the average juror, unqualified “to determine intelligently and to the best possible degree,” United States v. Lankford, 955 F.2d 1545,1558 (11th Cir. 1992) (Hoffman, J., dissenting), what to make of the fact that not a single shred of physical evidence was presented to link Frazier to the alleged victim qua victim in this case. His testimony would have assured against any tendency to over- or underestimate the value of this finding; indeed, the lack of forensic evidence could neither exonerate nor condemn Frazier of the rape, but only failed to substantiate it. To exclude such helpful testimony on the inappropriate ground relied on by the district court was manifestly reversible error.
The trial court also refused Tressel's proffered testimony that “it would be expected that some transfer or either hairs or seminal fluid would occur in this case” because it found this testimony unreliable for lack of scientific data. R5 at 24, Ex. 2 at 2. In particular, the district court faulted Tressel for not having rested his conclusion on any empirical study and disfavored his testimony because it was couched in qualitative terms rather than hard numbers or statistical data. See note 4, infra. This ruling was based on an incomplete understanding of the background required of an expert witness.
The text of Rule 702 dictates that expert status may be based on experience, and the Advisory Committee Notes dictate that experience alone “may . . . provide a sufficient foundation for expert testimony.” Rule 702 cmt. at 290. Without doubt, the Supreme Court’s ruling in Daubert imposes difficult gatekeeping duties on trial courts, one of which involves an exacting assault to the foundation of any proposed expert testimony to determine whether it is plumb or stands out of true, resting on shaky and unreliable ground. To survive this juridic ordeal and meet the standard of evidentiary reliability, expert testimony must be (1) “ground[ed] in the methods and procedures of science,” (2) authenticated by “more than subjective belief or unsupported speculation,” and (3) “supported by appropriate validation—i.e., ‘good grounds,’ based on what is known.” Daubert, 509 U.S. at 590, 113 S. Ct. at 2795. “[T]he trial court must scrutinize not only the principles and methods used by the expert, but also whether those principles and methods have been properly applied to the facts of the case.” Fed. R. Evid. 702 advisory committee’s note, 2000 amends. While the court must focus “solely on principles and methodology, not on the conclusions that they generate,” Daubert, 509 U.S. at 594, 113 S. Ct. at 2797, “conclusions and methodology are not entirely distinct from one another,” and “nothing . . . requires a district court to admit opinion evidence that 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.” Gen. Elec. Co. v. Joiner, 522 U.S. 136, 146, 118 S. Ct. 512, 519 (1997).
This pre-trial by fire “applies not only to testimony based on ‘scientific’ knowledge, but also to testimony based on ‘technical’ and ‘other specialized’ knowledge.” Kumho Tire, 526 U.S. at 141, 119 S. Ct. at 1171. Thus, all expert opinion “must be the product of reliable principles and methods that are reliably applied to the facts of the case.” Fed. R. Evid. 702, advisory committee notes, 2000 amends. “The trial judge in all cases of proffered expert testimony must find that it is properly grounded, well-reasoned, and not speculative before it can be admitted. The expert’s testimony must be grounded in an accepted body of learning or experience in the expert’s field, and the expert must explain how the conclusion is so grounded.” Id. (emphasis mine).
This uncompromising emphasis on reliability does not mean, however, that the personal experience or knowledge of the expert alone is not to be trusted. “To the contrary, the text of Rule 702 expressly contemplates that an expert may be qualified on the basis of experience. In certain fields, experience is the predominant, if not sole, basis for a great deal of reliable expert testimony.” Id. (emphasis mine). Indeed, “there are many different kinds of experts, and many different kinds of expertise.” Kumho Tire, 526 U.S. at 150, 119 S. Ct. at 1175. Even after Kumho Tire, “there is no question that an expert may still properly base his testimony on ‘professional study or personal experience.’” Maiz v. Virani, 253 F.3d 641, 668-69 (11th Cir. 2001) (holding that expert testimony on the “passport-stamping practices of Mexican immigration officials . . . based largely on [the expert’s] personal experience rather than verifiable testing or studies” was admissible) (emphasis mine).
However, this type of expert testimony generates certain difficulties in evaluating its reliability: “Some types of expert testimony will not rely on anything like a scientific method, and so will have to be evaluated by reference to other standard principles attendant to the particular area of expertise.” Fed. R. Evid. 702 advisory committee notes, 2000 amends. “[A]n expert’s qualifications and the reliability of his testimony do not always separate into a clear dichotomy,” United States v. Jones, 107 F.3d 1147, 1160 (6th Cir. 1997), and, in fact, are often blurred in the case of experience-based expert testimony. Where “the relevant reliability concerns may focus upon personal knowledge or experience,” Kumho Tire, 526 U.S. at 150, 119 S. Ct. at 1175, “inquiries into an expert’s qualifications, the reliability of his proffered opinion and the helpfulness of that opinion” frequently overlap to a significant degree. Quiet Tech. DC-8, Inc. v. Hurel-Dubois UK Ltd., 326 F.3d 1333, 1341 (11th Cir. 2003).
Even so, these “are distinct concepts that courts and litigants must take care not to conflate.” Id. “The trial court’s gatekeeping function requires more than simply taking the expert’s word for it.” Fed. R. Evid. 702 advisory committee notes, 2000 amends. (citation and internal quotation marks omitted). All experts, “whether basing testimony upon professional studies or personal experience, [must] employ[] in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.” Kumho Tire, 526 U.S. at 152, 119 S. Ct. at 1176. Courts must be creative when applying this panoptic principle, more accommodating in theory than in practice. While the Court in Daubert developed four, non-exhaustive measures of reliability,16 it emphasized that “[t]he inquiry envisioned by Rule 702 is . . . a flexible one.” 509 U.S. at 594, 113 S. Ct. at 2797. “[T]hose factors do not all necessarily apply even in every instance in which the reliability of scientific testimony is challenged.” Kumho Tire, 526 U.S. at 151, 119 S. Ct. at 1175. Whether they do “depend[s] on the nature of the issue, the expert’s particular expertise, and the subject of his testimony.” Id. at 150, 119 S. Ct. at 1175 (citation and internal quotation marks omitted).17 In short, while adapting the reliability inquiry to the nature of the testimony proffered, courts must still look long and hard at the expert’s principles and methods:
For example, when a law enforcement agent testifies regarding the use of code words in a drug transaction, the principle used by the agent is that participants in such transactions regularly use code words to conceal the nature of their activities. The method used by the agent is the application of extensive experience to analyze the meaning of the conversations. So long as the principles and methods are reliable and applied reliably to the facts of the case, this type of testimony should be admitted.
Fed. R. Evid. 702 advisory committee's notes, 2000 amends.
Case law is replete with judicially-sanctioned instances of this type of deductive reasoning. For instance, physicians and other professionals,18 valuation experts,19 experts on industry customs and practices,20 and handwriting analysts21 are often permitted to derive their conclusions in this fashion. After all, “[e]xperts of all kinds tie observations to conclusions through the use of what Judge Learned Hand called ‘general truths derived from . . . specialized experience,’” id. at 148, 119 S. Ct. at 1174 (citation omitted), and “no one denies that an expert might draw a conclusion from a set of observations based on extensive and specialized experience.” Id. at 156, 119 S. Ct. at 1178.
Considering the four, non-exhaustive measures of reliability developed by the Daubert Court, “[g]eneral acceptance in the community is an important factor in evaluating an expert’s methodology and courts particularly emphasize this Daubert factor when reliability focuses on experience.” Groobert v. President & Dirs. of Georgetown Coll., 219 F. Supp. 2d 1, 8 (D.C. 2002). The other Daubert factors often recede in importance.22 “The more subjective and controversial the expert’s inquiry, the more likely the testimony should be excluded as unreliable.” Fed. R. Evid. 702 advisory committee notes, 2000 amends. By the same token, the less controversial a conclusion, the more likely it is reliable. For example, it may “be useful to ask even of a witness whose expertise is based purely on experience, say, a perfume tester able to distinguish among 140 odors at a sniff, whether his preparation is of a kind that others in the field would recognize as acceptable.” Kumho Tire, 526 U.S. at 151, 119 S. Ct. at 1176. Therefore, “that an expert’s opinion is not based on statistical studies does not render that opinion inadmissible, provided that . . . the testimony is based on reasoning or methodology generally accepted within a particular profession or discipline.”23 Katt v. City of New York, 151 F. Supp. 2d 313, 356 (S.D.N.Y. 2001).
This is all the more true, as in this case, where probative quantitative studies are unavailable. For instance, one court refused to admit a physician’s statistical testimony based on general experience. “To allow doctors to testify about specific statistical or medical questions and base their testimony only on general experience would be to say that doctors are qualified experts on every medical subject merely because they wear white coats.” Erickson, 131 F. Supp. 2d at 999. But the same court permitted similarly based qualitative testimony:
Although mere experience in the field is not a reliable basis for . . . specific statistical . . . opinions . . . , here [the] opinion does not concern a specific statistic, but instead concerns the common knowledge in the field at the time. Experts have knowledge of the standards that govern their fields—that is part of what qualifies them as experts. . . . Although it would be ideal to have a citation to some medical publication to support th[e] proposition, [an expert] may testify about the standards or common knowledge of the [relevant academic] community . . . .
Id. at 1001. The Third Circuit likewise recognized that an expert’s “testimony is neither conjecture nor speculation” merely because there is no available publication to substantiate it if the testimony is “well recognized by the scientific community,” “not a novel scientific theory,” and “supported by widely accepted scientific knowledge,” and the expert “relied on general experience and readings, general medical knowledge, standard textbooks, and standard references.” Kannankeril v. Terminix Internat’l, Inc., 128 F.3d 802, 809 (3d Cir. 1997). Thus, expert opinion is not inherently unreliable merely for want of empirical studies if the information is commonplace in the field and “[s]tatistical methods are . . . not invariably used in such research.” Katt, 151 F. Supp. 2d at 357. Where “experience-based studies are generally accepted in the industry,” a “court cannot penalize [a litigant] for the lack of scientific or academic studies and public reports on the topic. . . .” Groobert, 219 F. Supp. 2d at 9, 11; accord Benedi v. McNeil-P.P.C., Inc., 66 F.3d 1378, 1385 (4th Cir. 1995) (holding that a “defendant should not be allowed ‘to escape liability simply because . . . there are, as yet, no . . . studies concerning [the specific subject area]’”) (citation omitted).
A useful construct is to imagine these two factors—whether the principle is common knowledge in the field and whether quantitative studies are available—as positioned within a four-part box. Just as no trial court would abuse its discretion by refusing to admit expert testimony considered experimental or speculative in the field for which quantitative studies were available,24 a trial court would most certainly abuse its discretion in many instances—like this one—by refusing to admit qualitative testimony for want of statistical support where the analytic assumptions were widely-held and relevant and probative statistical data unavailable.
The district court in this case did not question Tressel’s experience—his participation in 150 sexual assault cases and thousands of crime scene investigations—or the application of that experience to the undisputed facts of the case—the absence of any physical evidence to link Frazier to the crime of rape. The court instead forbade his testimony because it was stated qualitatively, not quantitatively, and not because he failed to cite any authority in the field for the proposition. See note 2, infra. That certain symptoms are indicative of particular illnesses, that certain customs and practices are frequently used in particular industries, legal or illegal, or that certain patterns of handwriting are distinctive have rarely been challenged as an unreliable basis for expert testimony just because they are not explicitly validated by quantitative research; even where such quantitative data could have been collected (e.g., the Government could collect data as to how drug dealers, money launderers, etc., do business based on collective data from case studies). Courts recognize that such principles are commonly known, widely-accepted, and often taken for granted in the relevant academic community. They need not be substantiated empirically because they have risen to the rank of platitudes within their respective fields.
This is what the Supreme Court meant when it instructed trial courts to ensure that an expert relying on personal experience “employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.” Kumho Tire, 526 U.S. at 152, 119 S. Ct. at 1176. What physician, for example, would be laughed out of a medical conference for asserting without supporting statistical data that he would expect the cause of classic flu-like symptoms to be, of all things, the flu? Yet, this is precisely what the district court did in response to Mr. Tressel’s testimony based on the rather uncontroversial assumption in his field that an experienced forensic investigator would expect to find hair or semen transfer in a sexual assault of prolonged duration in cramped quarters where, as here, evidence was gathered from an uncontaminated and confined crime scene. This ruling—requiring an experience-based expert to substantiate his conclusions with scientific data or studies—was an abuse of discretion.
The trial court's Daubert error was compounded: it excluded Tressel's testimony relating to the import of the lack of forensic evidence found at the crime scene—on the ground that this conclusion was not supported by scientific data—and yet allowed the Government's witnesses to testify to this very issue—without similarly requiring scientific support for their conclusions. On rebuttal, the Government was allowed to convert two defense fact witnesses—the FBI agents—into experts. Like the defense's proffer of Tressel's testimony, the Government offered the FBI agents as experience-based experts who would be asked to testify as to the import of the lack of forensic evidence found at the crime scene.25 Over the defense's objection, the two agents, not surprisingly, testified that the lack of forensic evidence matching Frazier did not prove that he had not committed the alleged sexual assaults. R9-363, 371, 387.
“It is an abuse of discretion ‘to exclude the otherwise admissible opinion of a
During the Daubert hearing, Tressel expressed his opinion that the investigation of the crime scene was “thorough” and that proper “protocol for [a] rape examination was followed.” Id. at 22 (“the proffer”). Defense counsel then asked Tressel whether, based on all the information he reviewed about the crime, he had an “opinion as to whether or not the description of the sexual assault provided by [the victim] . . . [was] accurate?” Id. at 23-24. Tressel responded that, “based on my review of the available documents, it is my professional opinion that there is no forensic evidence to substantiate the claim of rape in this case.” Id. at 24. Asked if he had “an opinion about whether or not a rape occurred,” id. at 25, Tressel responded that he “s[aw] no forensic evidence to substantiate the claim of rape in this case,” id. Based on where the sexual assault allegedly occurred [the passenger compartment of a small car], the amount of sexual contact involved, and the evidence examined by Tressel, he stated that he formed his conclusion because “[t]here should have been some transfer of either hairs, fibers or fluids between the victims in this case.” Id. at 27 (emphasis mine).
Recall that the FBI laboratory found absolutely no transfer of hair (pubic, body, or head) or fluid, despite a closed and confined collection site and meticulous collection protocol. See R9 at 343-44, 352, 356-58.
The academic literature relied upon by Tressel support his contention that the following types of evidence “appear with frequency in sexual assault cases”: “hairs, fibers, blood, semen, and saliva.” ROBERT R. HAZELWOOD & ANN WOLBERT BURGESS, PRACTICAL ASPECTS OF RAPE INVESTIGATION : A MULTIDISCIPLINARY APPROACH 97 (1987). In fact, “[t]he type of physical evidence probably most frequently associated with sexual assault investigations is semen.” Id. at 111. Moreover, “especially if there was physical force, hair is frequently found as evidence.” JAMES E. DOYLE, WISCONSIN DEP'T OF JUSTICE , PHYSICAL EVIDENCE HANDBOOK 138 (5th ed. 1993).
A review of the following quoted portions of the Daubert hearing, however, clearly demonstrates that the trial court did in fact require a scientific basis for Tressel's testimony. Perhaps the majority can point and quote directly from the record for the reader, as opposed to the “our-review-of-the-entire-record-suggests” approach to justify its unjustifiable conclusion that the trial court required scientific evidence—even in the face of its own concession.
Court: Taking Defendant's Exhibit Number 2 [Tressel's Report of Findings], and using that as the basis for my rulings, . . . I have no problems with his expertise as he is obviously a very qualified criminal investigator. . . .
But when it comes to the conclusions that you propose to offer him for, I believe that's exactly what the line of cases beginning with Daubert are aimed at, and I guess as the gatekeeper, I won't open it for those paragraphs [the last two full paragraphs on page 2 and the first two paragraphs on page 3 of Tressel's report, R5 at 24, Ex. 2] that I am talking about. . . .
Defense Counsel: Your honor, I see it as the converse to the FBI Agent or the DEA Agent, for instance, in a drug case that says typically based on my experience in a drug case, we expect to see pagers, we expect to see baggies, we expect to see code in their talk on the telephone, we expect them to see rendezvous at the fast food restaurants. All the stuff that we typically see that is based on their experience. . . .
Court: Now, I do have a problem and particularly if there is any scientific evidence that shows that in 99 percent of the time you find pubic hair, I would have no problem with that, but he has no study. . . .
I have no problem with him saying that's what they're looking for, but I do have a problem with him saying that that's what's found, and if it's not there, I don't believe there was a rape, and I'm not going to allow that.
Defense: But he's only saying it doesn't corroborate her claim of rape, and it seems to me that those concerns that he didn't do a scientific study are issues for cross-examination.
And the government is distressed or objecting because he is too specific rather than talking in broad terms. Where I would have thought that the reason that he is narrowing it to his opinion to that the physical evidence does not corroborate her story is a very specific statement without him drawing the conclusion that she wasn't raped, but he's saying that it doesn't support her story, doesn't substantiate her story.
Court: Well, what you're trying to do is get a witness to testify to what you should be arguing. . . .
Defense: But how is a lay jury going to know whether or not you should be finding this stuff, some trace evidence, some fluid evidence.
Court: If you have any scientific evidence that would indicate you should, I have no problem, as I said, with his testifying that's what they look for, but when you start trying to prove that there is no case because they didn't find it, you have got to have something more than just his opinion. You need something showing some study.
I have no idea whether - - I don't have enough to tell me how often that is, and I have no basis of knowing, and based upon what you've presented today, I would not and will not allow it. I don't think that helps the jury.
R5 at 64, 66-69 (emphasis mine).
While limited in scope, application, and probativeness, examples of the scientific literature available (other than the two sources relied upon by Tressel) are principally two academic articles. One article studied the rate of pubic hair transfers “following one episode of sexual intercourse by each of 15 volunteer test couples”—a small sample size in a controlled environment. Mary-Jacque Mann, Hair Transfers in Sexual Assault: a Six-Year Case Study, 35 J. FORENSIC SCI. 951, 953 (1990). This study admitted that “[p]ublished controlled hair transfer studies are a valuable source of clarifying information, but . . . such studies are disappointingly few in number.” Id. at 951. This article also conceded that “controlled transfer studies and the results of casework examinations should not be given equal weight.” Id. at 955 (emphasis mine).
A second, more recent article measured “the frequency of pubic hair transfer between a limited number of consenting heterosexual partners”—another admittedly “limited study.” David L. Exline, M.S.F.S., et al., Frequency of Pubic Hair Transfer During Sexual Intercourse, 43 J. FORENSIC SCI. 505, 507 (1998). The article made two conclusions: “[f]irst, pubic hair transfer does occur during sexual intercourse, and is significant forensic evidence when found. Second, further studies in the area of hair transfer frequencies are needed to better evaluate hair transfer evidence.” Id. at 507.
While this study explained that “[i]t is well known that pubic hairs may be transferred during certain sexual offenses,” it also admitted that “[f]ew controlled studies have been reported which could allow predictions of how frequently examiners might expect to observe such transfers.” Id. It also conceded that “[w]ithout additional studies, it is not clear that our results with a limited number of people would be found if larger numbers of individuals were examined, even under the controlled conditions described.” Id. (emphasis mine). Importantly, the article did note that “[p]rior to this study [i.e., before 1998], research concerning the transfer frequency of pubic hair was based on either forensic casework or limited human subject data” and “[u]ntil now, when asked in court about the frequency of pubic hair transference, experts could rely only on experience because of the lack of scientific literature.” Id. (emphasis mine). But this study was also of little probative value in that it examined the rate of hair transfer of “six Caucasian couples who collected their pubic hair combings immediately following intercourse.” Id. at 505.
The relevant academic literature cited by these studies also reveals significant inconsistencies in reported transfer rates between these and the few other studies that have been performed. Indeed, the rates ranged from zero to forty-five percent. See id. at 506; Mann, supra, at 953. If applied rigidly to specific cases of alleged rape, each with their dissimilar circumstances and variables, these studies may be a significant source of potential error. Overall, the paucity of, inconsistency between, and lack of appropriate controls and common situational variables in these studies demonstrate that the body of knowledge in this area is still in its infancy. By comparison, the qualitative testimony offered by Tressel would have been relatively inoffensive, unobjectionable, and hardly polemical, as evidenced by its wholesale endorsement by one of the field’s leading textbooks.
The Advisory Committee Notes to Rule 702 delineate five additional factors in determining reliability: (1) Whether the testimony “grow[s] naturally and directly out of research [experts] have conducted independent of the litigation, or whether they have developed their opinions expressly for purposes of testifying”; (2) “Whether the expert has unjustifiably extrapolated from an accepted premise to an unfounded conclusion”; (3) “Whether the expert has adequately accounted for obvious alternative explanations”; (4) “Whether the expert is being as careful as he would be in his regular professional work outside his paid litigation consulting”; and (5) “Whether the field of expertise claimed by the expert is known to reach reliable results for the type of opinion the expert would give.” Fed R. Evid. 702 advisory committee's notes, 2000 amends. (citations and internal quotation marks omitted).