dissenting:
The question at issue today is whether the district court abused its discretion in refusing to admit certain testimony proffered by Robert Tressel, the defense’s expert forensic investigator. Although the majority answers this question affirmatively, I cannot conclude, based on the record before me, that the district court’s decision to exclude this evidence was “ ‘manifestly erroneous.’” General Elec. Co. v. Joiner, 522 U.S. 136, 142, 118 S.Ct. 512, 517, 139 L.Ed.2d 508 (1997) (quoting Congress & Empire Spring Co. v. Edgar, 99 U.S. 645, 658, 25 L.Ed. 487 (1878)). Accordingly, I respectfully dissent.
Sometime after eight o’clock on the evening of October 31, 2000, an eighteen year old, student' (“the victim”) stopped at a Wal-Mart in Cornelia, Georgia to check the price of Halloween candy. Upon leaving the store she unlocked her car, and as she was about to get into the vehicle she was approached by appellant Richard Junior Frazier.' Frazier carried a knife in his right hand, and asked the victim: ‘Will you take me where I want to go?” Having no choice, the victim responded affirmatively. With Frazier sitting in the back seat directly behind her, the victim, at appellant’s direction, drove the two of them to a secluded, wooded area. Without exiting the vehicle, Frazier, again brandishing the knife, instructed her to remove her pants and underpants. Fearing for her life, the victim complied, and Frazier proceeded to rape her variously and repeatedly in a crime of unspeakable brutality. All told, Frazier subjected the victim to eleven acts of sexual assault in her own car.
When he was finished, Frazier drove the two of them north on U.S. Highway 441 toward North Carolina. By this time the victim’s family had been alerted to her absence, and her father had gone looking for her. He spotted her vehicle, chased it for several miles and attempted to flag it down. Although he was unable to do so, he managed to attract the attention of a passing police officer, who attempted to pull the victim’s car over. Frazier then led police on a high speed pursuit through Franklin, North Carolina, and ultimately crashed into a power pole along the side of North Carolina Route 28.
On June 20, 2001, Frazier was convicted in the United States District Court for the Northern District of Georgia of interstate kidnapping, in violation of 18 U.S.C. § 1201(a)(1). Although evidence of the sexual assaults was presented by the government at trial, the only crime for which Frazier stood trial was kidnapping. Because Frazier previously had been convicted of more than one “serious violent felony,” 1 he was sentenced to mandatory life *1270imprisonment under the federal three strikes law, 18 U.S.C. § 3559(c)(l)(A)(i).
At trial, Frazier’s strategy was to discredit the victim’s allegations of sexual abuse, and thus, by implication, of kidnapping.2 As a means to this end, appellant offered the testimony of Robert Tressel, a forensic investigator. Tressel was prepared to testify to the effect that:
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.
The resulting laboratory findings in this case[] do not substantiate the claim of rape through forensic evidence. Till findings of the samples that were taken, all of which are essentially routine rape investigation procedures, were negative in finding a transfer of seminal fluid or hair from the defendant in this case. The medical examination of the victim only shows evidence of sexual activity on the part of the victim at some time prior to the examination taking place. The documented finding of bruising around the labia major indicates that the bruising may be substantially older than only a few hours.
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. The only indication that any type of sexual activity occurred is the redness around the labia major and the redness of the cervix. These two injuries, in and of themselves, can occur during routine normal sexual activity. [The victim’s] medical records indicate that she had sexual intercourse on 10/29/2000.
Tressel’s Report of Findings at 2-3.
After an extensive Daubert hearing, the district court found Tressel to be an “obviously very qualified criminal investigator” and permitted him to testify concerning the forensic procedures that were employed in examining the crime scene and the physical findings that resulted from those procedures. However, it refused to allow him to offer an ultimate opinion as to whether the victim’s allegations of sexual assault were supported by the forensic evidence collected. The court reasoned that Tressel had not established the reliability of his conclusions, as his statement that “it would be expected that some transfer of either hairs or seminal fluid would occur in this case ” was simply too vague to permit a reasonable juror to competently assess his opinion as to the significance of the fact that no such hairs or fluids were found on the victim’s person or in her automobile. Indeed, the district court explicitly said that “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 [Tressel] has no study. He just says ... in a very nebulous statement that ... [pubic hair] was commonly found [in cases where the amount of sexual contact alleged by the victim actually transpired].” The court also disallowed Tressel from testifying as to the source of any cervical or labial injury because he was not a medical expert.3
*1271The majority holds that by excluding Tressel’s testimony that the absence of seminal fluid or pubic hairs belonging to Frazier on the victim or in the car cast into doubt the victim’s claim of sexual assault, the district court deprived appellant of a fundamentally fair trial. It says that “[t]he transcript of the Daubert hearing reveals that the district court treated a scientific background as a prerequisite to expert status,” and that its “decision to exclude Tressel’s testimony is based on an incomplete understanding of the background required of an expert witness.” The majority then sets forth the three-prong test for the admissibility of expert testimony articulated in City of Tuscaloosa v. Harcros Chems., Inc., 158 F.3d 548, 562 (11th Cir.1998), applies it, and concludes that each of the City of Tuscaloosa factors is satisfied in this case.
The majority’s analysis suffers from two basic flaws. First, I believe it misconstrues the basis for the district court’s exclusion of Tressel’s testimony, and thus its discussion of the possibility of qualifying a witness as an expert through experience, although correct, is largely irrelevant to the facts at bar. Second and more fundamentally, the majority fails to adhere to the Supreme Court’s clear admonition that under the abuse of discretion standard a district court’s evidentiary rulings must remain undisturbed absent manifest error. See Joiner, 522 U.S. at 142, 118 S.Ct. at 517. Indeed, it is by now axiomatic that the district court enjoys “considerable leeway” in making the ultimate decision to admit or exclude expert evidence. Kumho Tire Co., Ltd. v. Carmichael, 526 U.S. 137, 152, 119 S.Ct. 1167, 1176, 143 L.Ed.2d 238 (1999). Moreover, the Supreme Court has made abundantly clear that “[t]he trial court must have the same kind of latitude in deciding how to test an expert’s reliability ... as it enjoys when it decides whether or not that expert’s relevant testimony is reliable.” Id. (emphasis original). Thus, “[i]t is very much a matter of discretion with the trial court whether to permit the introduction of [expert] evidence, and we will not reverse the decision of the trial court regarding the exclusion or admission of such evidence unless the trial court’s decision is ‘manifestly erroneous.’” Michigan Millers Mut. Ins. Corp. v. Benfield, 140 F.3d 915, 921 (11th Cir.1998).
As the majority notes, we engage in a three part inquiry to determine the admissibility of expert testimony under Fed. R.Evid. 702. Specifically, we must consider whether:
(1) [T]he 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, 158 F.3d at 562 (citing Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 589, 113 S.Ct. 2786, 2794-95, 125 L.Ed.2d 469 (1993)); see also Maiz v. Virani, 253 F.3d 641, 665 (11th Cir.2001) (same).
Preliminarily, I have no quarrel with the majority’s conclusion that the first and third elements of this test are satisfied here. It is indisputable that by virtue of his experience Tressel was a qualified forensic investigator, and his testimony likely would have been helpful to the jury.However, I cannot accept the majority’s observation that the district court failed to recognize this. At no point did the trial court refuse to qualify Tressel as an expert in forensic criminal investigation because his expertise was based on experience *1272rather than a scientific background. Indeed, the district court’s concern was not with Tressel’s qualification to offer expert opinions on this subject generally, but rather with the basis for — i.e., reliability of — his specific opinion that the forensic evidence did not support the victim’s allegations. The mere fact that a testifying witness is properly afforded expert status does not mean that every opinion offered by that witness will be admissible under the test outlined above. Put differently, it is possible for a particular opinion proffered by a genuinely qualified expert to be unreliable. See, e.g., McCorvey v. Baxter Healthcare Corp., 298 F.3d 1253, 1256 (11th Cir.2002) (“Daubert requires that trial courts act as ‘gatekeepers’ to ensure that speculative, unreliable expert testimony does not reach the jury.”); Tompkins v. Moore, 193 F.3d 1327, 1337-38 (11th Cir.1999) (describing conditions under which an expert’s opinion may be considered unreliable). Accordingly, it is the reliability of the specific opinion proffered by Tres-sel' — not his expert qualifications — that are genuinely at issue in this appeal.
It is this question of reliability that the second prong of the City of Tuscaloosa test is designed to answer, and it is on this issue that I disagree fundamentally with the majority. As alluded to, supra, the majority’s primary error in resolving this issue lies in its refusal to accord sufficient deference to the district court’s determination as to the reliability of Tressel’s opinion.
It is a basic tenet of the law of evidence that “[pjroposed [expert] testimony must be supported by appropriate validation— i.e., ‘good grounds,’ based on what is known.” Daubert, 509 U.S. at 590, 113 S.Ct. at 2795. Thus, “the Rules of Evidence — especially Rule 702 — [assign] 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. This requirement that expert testimony be reliable — that is, based on an adequate methodological foundation — applies whether the “expert relies on the application of scientific principles ... [or on] skill- or experience-based observation.” Kumho Tire, 526 U.S. at 151, 119 S.Ct. at 1176 (citation omitted); see also Allison v. McGhan Med. Corp., 184 F.3d 1300, 1315-17 (11th Cir.1999) (discussing the foundation required for expert testimony on causation in a tort case); Maiz, 253 F.3d at 664-65 (finding that the district court did not err by allowing an expert to base his opinion on an assumption that could be challenged by the opposing party).
The Court in Daubert proceeded to describe in general terms the contours of this reliability inquiry, noting the especial pertinence of: (1) whether the expert’s theory can be and has been tested; (2) whether the theory has been subjected to peer review and publication; (3) the known or potential rate of error of the particular scientific technique; and (4) whether the technique is generally accepted in the scientific community. Daubert, 509 U.S. at 593-94, 113 S.Ct. at 2796-97. Although the Supreme Court explicitly cautioned that these factors do not exhaust the universe of considerations that bear on reliability, we have noted that where possible they at least should be considered. See McCorvey, 298 F.3d at 1256.
In this case, Tressel opined simply that “[w]ith 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 .... ” Tressel’s Report of Findings at 2 (emphasis added). However, a careful review of the transcript of the Daubert hearing and Tressel’s expert report show that Tressel failed to provide any specific foundation for his assertions that hair and *1273fluids were “commonly” found in sexual assault cases and that, therefore, the lack of such evidence supported the conclusion that there had not been an assault. Quite simply, Tressel was unable to offer any reliable information regarding the rates at which hairs or fluids are transferred during sexual contact. I believe that it was this lack of any verifiable basis for Tres-sel’s opinion as to the victim’s credibility that concerned the district court. It said: “[I]f there is any scientific evidence that shows that in 99 percent of the time, you And pubic hair, I would have no problem with that, but he [Tressel] has no study. He just says ... in a very nebulous statement that ... [pubic hair] was commonly found [in cases where the amount of sexual contact alleged by the victim actually transpired].” The court subsequently continued:
If you have any scientific evidence that would indicate you should [find pubic hairs or seminal fluid under circumstances such as those described by the victim], I have no problem ... 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 ... how often [hairs or bodily fluids are found], and I have no basis of knowing, and base upon what you’ve presented today, I would not and will not allow it. I don’t think that helps the jury.
I don’t know what the percentage is. Are you going to say then there is a 50% chance [the victim is] not credible, or there’s a 25% [chance] or a 75% [chance] she’s not credible!?] I have difficulty with that, and I just don’t think that under those circumstances I would admit it.
As evidenced by the foregoing passage, Tressel provided the district court with literally no basis for ascertaining the reliability of his proffered testimony. In the terms employed by Daubert, the district court could not have ascertained by any means — scientific or otherwise — the foundations of Tressel’s testimony. Nor could it have known whether his ideas had been subjected to peer review or the percentage of cases in which his opinion had been erroneous. Indeed, it is evident that the district court was referring to this last shortcoming in Tressel’s proffered testimony when it repeatedly asked “what the percentage is.” Moreover, Tressel presented no evidence as to the general acceptance of his opinion concerning the correlation between the presence of seminal fluid or pubic hairs and the amount of sexual contact described by the victim.
Importantly, it would not have been necessary — nor, contrary to the majority’s suggestion, do I believe the district court deemed it necessary' — -to establish such reliability via scientific means, e.g., a formal study. See Kumho Tire, 526 U.S. at 152, 119 S.Ct. at 1176 (discussing the possibility of. satisfying Daubert’s reliability inquiry through a showing based on “personal experience”); United States v. Hankey, 203 F.3d 1160, 1169 (9th Cir.2000) (noting, in a case concerning the reliability of expert testimony regarding the behavioral norms of street gangs, that “[t]he Daubert factors ... simply are not applicable to this kind of testimony, whose reliability depends heavily on the knowledge arid experience of the expert, rather than the methodology or theory behind it”).
The district court admittedly made several references to a study as a potential means of establishing the reliability of Tressel’s testimony, and those statements certainly suggest that a scientific study would have been one way for Tressel to *1274demonstrate the reliability of his opinion. However, read in context, they cannot be taken to mean that only scientific evidence would provide an adequate foundation for Tressel’s testimony. Indeed, the district court never indicated that Tressel’s experience could not also have provided a proper foundation if it had been presented in such a way as to support the testimony. In fact, as the majority explicitly notes, the court properly permitted Anthony Orona-to, an FBI forensic DNA examiner, to testify for the defense. The reliability of Oronato’s opinion was derived from his experience-based testimony that in “20 to 25 percent of [sexual assault] cases I don’t identify semen.” Had Tressel similarly testified that based on his experience he found hair or fluids in X% of similar cases, it would not have been an abuse of discretion under Fed.R.Evid. 702 to allow in his opinion that the forensic evidence did not support the victim’s allegations of sexual assault. However, he presented absolutely no such basis for opining as to the importance of the fact that no hairs or fluids were found in this case. Accordingly, Tressel’s testimony is meaningfully distinguishable from that given by Oronato and was properly excluded by the district court.
In reaching the opposite conclusion, the majority states, as if it were somehow self-evident, that “[r]eliability in this particular case is established by Tressel’s precision and logic.” In particular, the majority predicates its finding of reliability on Tres-sel’s assertions that “(1) the most common forms of forensic evidence found at the scene of a sexual assault are the hairs and fluids of the perpetrator, and (2) no evidence of Frazier’s hair or fluid were found inside [the victim’s] vehicle or on her person, so (3) [the victim’s] allegations of sexual assault are not substantiated by the most likely forms of forensic evidence.” The problem with this analytical mode is that a crucial step — call it (1.5) — is missing. For Tressel’s testimony to have been reliable under Fed.R.Evid. 702, he necessarily would have established with some measure of precision how common it is to find such hairs and fluids. Yet he never even testified as to how often, in his experience, these types of forensic evidence are found in cases like this one. The absence of any methodological foundation for his opinion rendered this portion of Tressel’s testimony objectively unverifiable, and prevented the jury from making an informed assessment of its significance. I can discern no abuse of discretion, let alone manifest error, in the district court’s conclusion that Tressel’s proffered testimony on this matter was unreliable and therefore inadmissible.
The majority’s holding that the district court abused its discretion eviscerates the critical gatekeeping role played by the trial court in determining the admissibility of expert opinion testimony and unapologeti-cally substitutes its own reliability assessment for that of the district court in direct contravention of the Supreme Court’s admonition that an appellate court is not empowered to do so. See Kumho Tire, 526 U.S. at 152, 119 S.Ct. at 1176. And it does so with no real analysis of how or why Tressel’s specific opinion as to the credibility of the victim’s allegations of sexual abuse is in fact reliable.
Accordingly, I respectfully dissent.
. Appellant had twice previously been convicted in the Georgia courts of each of the following crimes, for a total of six prior convictions: armed robbery, robbery and aggra-valed assault. Because this kidnapping was Frazier’s first federal conviction, it represent*1270ed the first time the government sought to have him sentenced under § 3559(c)( 1 )(A)(i).
. Frazier told police that the victim had offered to take him to North Carolina, but requested that he drive her car.
. I do not read the majority’s opinion to designate this determination as incorrect, nor do I think that there is any genuine question that Tressel was unqualified to testify as to these medical issues. See Transcript of June 11, 2001 Daubert hearing at 4-14 (Tressel describing his experience as a forensic investigator, not a medical expert).