[ Breyer ]
[ Scalia ]
[ Stevens ]
KUMHO TIRE COMPANY, LTD., et al., PETITIONERS
v. PATRICK CARMICHAEL, etc., et al.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE ELEVENTH CIRCUIT
[March 23, 1999]
Justice Breyer delivered the opinion of the Court.
In Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), this Court focused upon the admissibility of scientific expert testimony. It pointed out that such testimony is admissible only if it is both relevant and reliable. And it held that the Federal Rules of Evidence assign to the trial judge the task of ensuring that an experts testimony both rests on a reliable foundation and is relevant to the task at hand. Id., at 597. The Court also discussed certain more specific factors, such as testing, peer review, error rates, and acceptability in the relevant scientific community, some or all of which might prove helpful in determining the reliability of a particular scientific theory or technique. Id., at 593594.
This case requires us to decide how Daubert applies to the testimony of engineers and other experts who are not scientists. We conclude that Dauberts general holding setting forth the trial judges general gatekeeping obligationapplies not only to testimony based on scientific knowledge, but also to testimony based on technical and other specialized knowledge. See Fed. Rule Evid. 702. We also conclude that a trial court may consider one or more of the more specific factors that Daubert mentioned when doing so will help determine that testimonys reliability. But, as the Court stated in Daubert, the test of reliability is flexible, and Dauberts list of specific factors neither necessarily nor exclusively applies to all experts or in every case. Rather, the law grants a district court the same broad latitude when it decides how to determine reliability as it enjoys in respect to its ultimate reliability determination. See General Electric Co. v. Joiner, 522 U.S. 136, 143 (1997) (courts of appeals are to apply abuse of discretion standard when reviewing district courts reliability determination). Applying these standards, we determine that the District Courts decision in this casenot to admit certain expert testimonywas within its discretion and therefore lawful.
On July 6, 1993, the right rear tire of a minivan driven by Patrick Carmichael blew out. In the accident that followed, one of the passengers died, and others were severely injured. In October 1993, the Carmichaels brought this diversity suit against the tires maker and its distributor, whom we refer to collectively as Kumho Tire, claiming that the tire was defective. The plaintiffs rested their case in significant part upon deposition testimony provided by an expert in tire failure analysis, Dennis Carlson, Jr., who intended to testify in support of their conclusion.
Carlsons depositions relied upon certain features of tire technology that are not in dispute. A steel-belted radial tire like the Carmichaels is made up of a carcass containing many layers of flexible cords, called plies, along which (between the cords and the outer tread) are laid steel strips called belts. Steel wire loops, called beads, hold the cords together at the plies bottom edges. An outer layer, called the tread, encases the carcass, and the entire tire is bound together in rubber, through the application of heat and various chemicals. See generally, e.g., J. Dixon, Tires, Suspension and Handling 6872 (2d ed. 1996). The bead of the tire sits upon a bead seat, which is part of the wheel assembly. That assembly contains a rim flange, which extends over the bead and rests against the side of the tire. See M. Mavrigian, Performance Wheels & Tires 81, 83 (1998) (illustrations).
Carlsons testimony also accepted certain background facts about the tire in question. He assumed that before the blowout the tire had traveled far. (The tire was made in 1988 and had been installed some time before the Carmichaels bought the used minivan in March 1993; the Carmichaels had driven the van approximately 7,000 additional miles in the two months they had owned it.) Carlson noted that the tires tread depth, which was 11/32 of an inch when new, App. 242, had been worn down to depths that ranged from 3/32 of an inch along some parts of the tire, to nothing at all along others. Id., at 287. He conceded that the tire tread had at least two punctures which had been inadequately repaired. Id., at 258261, 322.
Despite the tires age and history, Carlson concluded that a defect in its manufacture or design caused the blow-out. He rested this conclusion in part upon three premises which, for present purposes, we must assume are not in dispute: First, a tires carcass should stay bound to the inner side of the tread for a significant period of time after its tread depth has worn away. Id., at 208209. Second, the tread of the tire at issue had separated from its inner steel-belted carcass prior to the accident. Id., at 336. Third, this separation caused the blowout. Ibid.
Carlsons conclusion that a defect caused the separation, however, rested upon certain other propositions, several of which the defendants strongly dispute. First, Carlson said that if a separation is not caused by a certain kind of tire misuse called overdeflection (which consists of underinflating the tire or causing it to carry too much weight, thereby generating heat that can undo the chemical tread/carcass bond), then, ordinarily, its cause is a tire defect. Id., at 193195, 277278. Second, he said that if a tire has been subject to sufficient overdeflection to cause a separation, it should reveal certain physical symptoms. These symptoms include (a) tread wear on the tires shoulder that is greater than the tread wear along the tires center, id., at 211; (b) signs of a bead groove, where the beads have been pushed too hard against the bead seat on the inside of the tires rim, id., at 196197; (c) sidewalls of the tire with physical signs of deterioration, such as discoloration, id., at 212; and/or (d) marks on the tires rim flange, id., at 219220. Third, Carlson said that where he does not find at least two of the four physical signs just mentioned (and presumably where there is no reason to suspect a less common cause of separation), he concludes that a manufacturing or design defect caused the separation. Id., at 223224.
Carlson added that he had inspected the tire in question. He conceded that the tire to a limited degree showed greater wear on the shoulder than in the center, some signs of bead groove, some discoloration, a few marks on the rim flange, and inadequately filled puncture holes (which can also cause heat that might lead to separation). Id., at 256257, 258261, 277, 303304, 308. But, in each instance, he testified that the symptoms were not significant, and he explained why he believed that they did not reveal overdeflection. For example, the extra shoulder wear, he said, appeared primarily on one shoulder, whereas an overdeflected tire would reveal equally abnormal wear on both shoulders. Id., at 277. Carlson concluded that the tire did not bear at least two of the four overdeflection symptoms, nor was there any less obvious cause of separation; and since neither overdeflection nor the punctures caused the blowout, a defect must have done so.
Kumho Tire moved the District Court to exclude Carlsons testimony on the ground that his methodology failed Rule 702s reliability requirement. The court agreed with Kumho that it should act as a Daubert-type reliability gatekeeper, even though one might consider Carlsons testimony as technical, rather than scientific. See Carmichael v. Samyang Tires, Inc., 923 F. Supp. 1514, 15211522 (SD Ala. 1996). The court then examined Carlsons methodology in light of the reliability-related factors that Daubert mentioned, such as a theorys testability, whether it has been a subject of peer review or publication, the known or potential rate of error, and the degree of acceptance within the relevant scientific community. 923 F. Supp., at 1520 (citing Daubert, 509 U.S., at 592594). The District Court found that all those factors argued against the reliability of Carlsons methods, and it granted the motion to exclude the testimony (as well as the defendants accompanying motion for summary judgment).
The plaintiffs, arguing that the courts application of the Daubert factors was too inflexible, asked for reconsideration. And the Court granted that motion. Carmichael v. Samyang Tires, Inc., Civ. Action No. 930860CBS (SD Ala., June 5, 1996), App. to Pet. for Cert. 1c. After reconsidering the matter, the court agreed with the plaintiffs that Daubert should be applied flexibly, that its four factors were simply illustrative, and that other factors could argue in favor of admissibility. It conceded that there may be widespread acceptance of a visual-inspection method for some relevant purposes. But the court found insufficient indications of the reliability of
the component of Carlsons tire failure analysis which most concerned the Court, namely, the methodology employed by the expert in analyzing the data obtained in the visual inspection, and the scientific basis, if any, for such an analysis. Id., at 6c.
It consequently affirmed its earlier order declaring Carlsons testimony inadmissable and granting the defendants motion for summary judgment.
The Eleventh Circuit reversed. See Carmichael v. Samyang Tire, Inc., 131 F.3d 1433 (1997). It review[ed]
de novo the district courts legal decision to apply Daubert. Id., at 1435. It noted that the Supreme Court in Daubert explicitly limited its holding to cover only the scientific context,
Kumho Tire petitioned for certiorari, asking us to determine whether a trial court may consider Dauberts specific factors when determining the admissibility of an engineering experts testimony. Pet. for Cert. i. We granted certiorari in light of uncertainty among the lower courts about whether, or how, Daubert applies to expert testimony that might be characterized as based not upon scientific knowledge, but rather upon technical or other specialized knowledge. Fed. Rule Evid. 702; compare, e.g., Watkins v. Telsmith, Inc., 121 F.3d 984, 990991 (CA5 1997), with, e.g., Compton v. Subaru of America, Inc., 82 F.3d 1513, 15181519 (CA10), cert. denied, 519 U.S. 1042 (1996).
In Daubert, this Court held that Federal Rule of Evidence 702 imposes a special obligation upon a trial judge to ensure that any and all scientific testimony is not only relevant, but reliable. 509 U.S., at 589. The initial question before us is whether this basic gatekeeping obligation applies only to scientific testimony or to all expert testimony. We, like the parties, believe that it applies to all expert testimony. See Brief for Petitioners 19; Brief for Respondents 17.
For one thing, Rule 702 itself says:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
This language makes no relevant distinction between scientific knowledge and technical or other specialized knowledge. It makes clear that any such knowledge might become the subject of expert testimony. In Daubert, the Court specified that it is the Rules word knowledge, not the words (like scientific) that modify that word, that establishes a standard of evidentiary reliability. 509 U.S., at 589590. Hence, as a matter of language, the Rule applies its reliability standard to all scientific, technical, or other specialized matters within its scope. We concede that the Court in Daubert referred only to scientific knowledge. But as the Court there said, it referred to scientific testimony because that [wa]s the nature of the expertise at issue. Id., at 590, n. 8.
Neither is the evidentiary rationale that underlay the Courts basic Daubert gatekeeping determination limited to scientific knowledge. Daubert pointed out that Federal Rules 702 and 703 grant expert witnesses testimonial latitude unavailable to other witnesses on the assumption that the experts opinion will have a reliable basis in the knowledge and experience of his discipline. Id., at 592 (pointing out that experts may testify to opinions, including those that are not based on firsthand knowledge or observation). The Rules grant that latitude to all experts, not just to scientific ones.
Finally, it would prove difficult, if not impossible, for judges to administer evidentiary rules under which a gatekeeping obligation depended upon a distinction between scientific knowledge and technical or other specialized knowledge. There is no clear line that divides the one from the others. Disciplines such as engineering rest upon scientific knowledge. Pure scientific theory itself may depend for its development upon observation and properly engineered machinery. And conceptual efforts to distinguish the two are unlikely to produce clear legal lines capable of application in particular cases. Cf. Brief for National Academy of Engineering as Amicus Curiae 9 (scientist seeks to understand nature while the engineer seeks natures modification); Brief for Rubber Manufacturers Association as Amicus Curiae 1416 (engineering, as an applied science, relies on scientific reasoning and methodology); Brief for John Allen et al. as Amici Curiae 6 (engineering relies upon scientific knowledge and methods).
Neither is there a convincing need to make such distinctions. Experts of all kinds tie observations to conclusions through the use of what Judge Learned Hand called general truths derived from specialized experience. Hand, Historical and Practical Considerations Regarding Expert Testimony, 15 Harv. L. Rev. 40, 54 (1901). And 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 experts testimony often will rest upon an experience confessedly foreign in kind to [the jurys] own. Ibid. The trial judges effort to assure that the specialized testimony is reliable and relevant can help the jury evaluate that foreign experience, whether the testimony reflects scientific, technical, or other specialized knowledge.
We conclude that Dauberts general principles apply to the expert matters described in Rule 702. The Rule, in respect to all such matters, establishes a standard of evidentiary reliability. 509 U.S., at 590. It requires a valid connection to the pertinent inquiry as a precondition to admissibility. Id., at 592. And where such testimonys factual basis, data, principles, methods, or their application are called sufficiently into question, see Part III, infra, the trial judge must determine whether the testimony has a reliable basis in the knowledge and experience of [the relevant] discipline. 509 U.S., at 592.
The petitioners ask more specifically whether a trial judge determining the admissibility of an engineering experts testimony may consider several more specific factors that Daubert said might bear on a judges gate-keeping determination. These factors include:
Whether a theory or technique can be (and has been) tested;
Whether it has been subjected to peer review and publication;
Whether, in respect to a particular technique, there is a high known or potential rate of error and whether there are standards controlling the techniques operation; and
Whether the theory or technique enjoys general acceptance within a relevant scientific community. 509 U.S., at 592594.
Emphasizing the word may in the question, we answer that question yes.
Engineering testimony rests upon scientific foundations, the reliability of which will be at issue in some cases. See, e.g., Brief for Stephen Bobo et al. as Amici Curiae 23 (stressing the scientific bases of engineering disciplines). In other cases, the relevant reliability concerns may focus upon personal knowledge or experience. As the Solicitor General points out, there are many different kinds of experts, and many different kinds of expertise. See Brief for United States as Amicus Curiae 1819, and n. 5 (citing cases involving experts in drug terms, handwriting analysis, criminal modus operandi, land valuation, agricultural practices, railroad procedures, attorneys fee valuation, and others). Our emphasis on the word may thus reflects Dauberts description of the Rule 702 inquiry as a flexible one. 509 U.S., at 594. Daubert makes clear that the factors it mentions do not constitute a definitive checklist or test. Id., at 593. And Daubert adds that the gatekeeping inquiry must be
Daubert itself is not to the contrary. It made clear that its list of factors was meant to be helpful, not definitive. Indeed, those factors do not all necessarily apply even in every instance in which the reliability of scientific testimony is challenged. It might not be surprising in a particular case, for example, that a claim made by a scientific witness has never been the subject of peer review, for the particular application at issue may never previously have interested any scientist. Nor, on the other hand, does the presence of Dauberts general acceptance factor help show that an experts testimony is reliable where the discipline itself lacks reliability, as, for example, do theories grounded in any so-called generally accepted principles of astrology or necromancy.
At the same time, and contrary to the Court of Appeals view, some of Dauberts questions can help to evaluate the reliability even of experience-based testimony. In certain cases, it will be appropriate for the trial judge to ask, for example, how often an engineering experts experience-based methodology has produced erroneous results, or whether such a method is generally accepted in the relevant engineering community. Likewise, it will at times 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.
We must therefore disagree with the Eleventh Circuits holding that a trial judge may ask questions of the sort Daubert mentioned only where an expert relies on the application of scientific principles, but not where an expert relies on skill- or experience-based observation. 131 F.3d, at 1435. We do not believe that Rule 702 creates a schematism that segregates expertise by type while mapping certain kinds of questions to certain kinds of experts. Life and the legal cases that it generates are too complex to warrant so definitive a match.
To say this is not to deny the importance of Dauberts gatekeeping requirement. The objective of that requirement is to ensure the reliability and relevancy of expert testimony. It is to make certain that an expert, whether basing testimony upon professional studies or personal experience, employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field. Nor do we deny that, as stated in Daubert, the particular questions that it mentioned will often be appropriate for use in determining the reliability of challenged expert testimony. Rather, we conclude that the trial judge must have considerable leeway in deciding in a particular case how to go about determining whether particular expert testimony is reliable. That is to say, a trial court should consider the specific factors identified in Daubert where they are reasonable measures of the reliability of expert testimony.
The trial court must have the same kind of latitude in deciding how to test an experts reliability, and to decide whether or when special briefing or other proceedings are needed to investigate reliability, as it enjoys when it decides whether that experts relevant testimony is reliable. Our opinion in Joiner makes clear that a court of appeals is to apply an abuse-of-discretion standard when it review[s] a trial courts decision to admit or exclude expert testimony. 522 U.S., at 138139. That standard applies as much to the trial courts decisions about how to determine reliability as to its ultimate conclusion. Otherwise, the trial judge would lack the discretionary authority needed both to avoid unnecessary reliability proceedings in ordinary cases where the reliability of an experts methods is properly taken for granted, and to require appropriate proceedings in the less usual or more complex cases where cause for questioning the experts reliability arises. Indeed, the Rules seek to avoid unjustifiable expense and delay as part of their search for truth and the jus[t] determin[ation] of proceedings. Fed. Rule Evid. 102. Thus, whether Dauberts specific factors are, or are not, reasonable measures of reliability in a particular case is a matter that the law grants the trial judge broad latitude to determine. See Joiner, supra, at 143. And the Eleventh Circuit erred insofar as it held to the contrary.
We further explain the way in which a trial judge may consider Dauberts factors by applying these considerations to the case at hand, a matter that has been briefed exhaustively by the parties and their 19 amici. The District Court did not doubt Carlsons qualifications, which included a masters degree in mechanical engineering, 10 years work at Michelin America, Inc., and testimony as a tire failure consultant in other tort cases. Rather, it excluded the testimony because, despite those qualifications, it initially doubted, and then found unreliable, the methodology employed by the expert in analyzing the data obtained in the visual inspection, and the scientific basis, if any, for such an analysis. Civ. Action No. 930860CBS (SD Ala., June 5, 1996), App. to Pet. for Cert. 6c. After examining the transcript in some detail, 923 F. Supp., at 1518519, n. 4, and after considering respondents defense of Carlsons methodology, the District Court determined that Carlsons testimony was not reliable. It fell outside the range where experts might reasonably differ, and where the jury must decide among the conflicting views of different experts, even though the evidence is shaky. Daubert, 509 U.S., at 596. In our view, the doubts that triggered the District Courts initial inquiry here were reasonable, as was the courts ultimate
For one thing, and contrary to respondents suggestion,
the specific issue before the court was not the reasonableness in general of a tire experts use of a visual and tactile inspection to determine whether overdeflection had caused the tires tread to separate from its steel-belted carcass. Rather, it was the reasonableness of using such an approach, along with Carlsons particular method of analyzing the data thereby obtained, to draw a conclusion regarding the particular matter to which the expert testimony was directly relevant. That matter concerned the likelihood that a defect in the tire at issue caused its tread to separate from its carcass. The tire in question, the expert conceded, had traveled far enough so that some of the tread had been worn bald; it should have been taken out of
service; it had been repaired (inadequately) for punctures;
and it bore some of the very marks that the expert said
indicated, not a defect, but abuse through overdeflection.
See supra, at 35; App. 293294. The relevant issue was
whether the expert could reliably determine the cause of
this tires separation.
Nor was the basis for Carlsons conclusion simply the general theory that, in the absence of evidence of abuse, a defect will normally have caused a tires separation. Rather, the expert employed a more specific theory to establish the existence (or absence) of such abuse. Carlson testified precisely that in the absence of at least two of four signs of abuse (proportionately greater tread wear on the shoulder; signs of grooves caused by the beads; discolored sidewalls; marks on the rim flange) he concludes that a defect caused the separation. And his analysis depended upon acceptance of a further implicit proposition, namely, that his visual and tactile inspection could determine that the tire before him had not been abused despite some evidence of the presence of the very signs for which he looked (and two punctures).
For another thing, the transcripts of Carlsons depositions support both the trial courts initial uncertainty and its final conclusion. Those transcripts cast considerable doubt upon the reliability of both the explicit theory (about the need for two signs of abuse) and the implicit proposition (about the significance of visual inspection in this case). Among other things, the expert could not say whether the tire had traveled more than 10, or 20, or 30, or 40, or 50 thousand miles, adding that 6,000 miles was about how far he could say with any certainty. Id., at 265. The court could reasonably have wondered about the reliability of a method of visual and tactile inspection sufficiently precise to ascertain with some certainty the abuse-related significance of minute shoulder/center relative tread wear differences, but insufficiently precise to tell with any certainty from the tread wear whether a tire had traveled less than 10,000 or more than 50,000 miles. And these concerns might have been augmented by Carlsons repeated reliance on the subjective[ness] of his mode of analysis in response to questions seeking specific
information regarding how he could differentiate between a tire that actually had been overdeflected and a tire that merely looked as though it had been. Id., at 222, 224225, 285286. They would have been further augmented by the fact that Carlson said he had inspected the tire itself for the first time the morning of his first deposition, and then only for a few hours. (His initial conclusions were based on photographs.) Id., at 180.
Moreover, prior to his first deposition, Carlson had issued a signed report in which he concluded that the tire had not been overloaded or underinflated, not because of the absence of two of four signs of abuse, but simply because the rim flange impressions . . . were normal. Id., at 335336. That report also said that the tread depth remaining was 3/32 inch, id., at 336, though the opposing experts (apparently undisputed) measurements indicate that the tread depth taken at various positions around the tire actually ranged from .5/32 of an inch to 4/32 of an inch, with the tire apparently showing greater wear along both shoulders than along the center, id., at 432433.
Further, in respect to one sign of abuse, bead grooving, the expert seemed to deny the sufficiency of his own simple visual-inspection methodology. He testified that most tires have some bead groove pattern, that where there is reason to suspect an abnormal bead groove he would ideally look at a lot of [similar] tires to know the groovings significance, and that he had not looked at many tires similar to the one at issue. Id., at 212213, 214, 217.
Finally, the court, after looking for a defense of Carlsons methodology as applied in these circumstances, found no convincing defense. Rather, it found (1) that none of the Daubert factors, including that of general acceptance in the relevant expert community, indicated that Carlsons testimony was reliable, 923 F. Supp., at 1521; (2) that its own analysis revealed no countervailing
factors operating in favor of admissibility which could outweigh those identified in Daubert, App. to Pet.
for Cert. 4c; and (3) that the parties identified no such factors in their briefs, ibid. For these three reasons
taken together, it concluded that Carlsons testimony was unreliable.
Respondents now argue to us, as they did to the District Court, that a method of tire failure analysis that employs a visual/tactile inspection is a reliable method, and they point both to its use by other experts and to Carlsons long experience working for Michelin as sufficient indication that that is so. But no one denies that an expert might draw a conclusion from a set of observations based on extensive and specialized experience. Nor does anyone deny that, as a general matter, tire abuse may often be identified by qualified experts through visual or tactile inspection of the tire. See Affidavit of H. R. Baumgardner 12, cited in Brief for National Academy of Forensic Engineers as Amici Curiae 16 (Tire engineers rely on visual examination and process of elimination to analyze experimental test tires). As we said before, supra, at 14, the question before the trial court was specific, not general. The trial court had to decide whether this particular expert had sufficient specialized knowledge to assist the jurors in deciding the particular issues in the case. 4 J. McLaughlin, Weinsteins Federal Evidence ¶702.05, p. 70233 (2d ed. 1998); see also Advisory Committees Note on Proposed Fed. Rule Evid. 702, Preliminary Draft of Proposed Amendments to the Federal Rules of Civil Procedure and Evidence: Request for Comment 126 (1998) (stressing that district courts must scrutinize whether the principles and methods employed by an expert have been properly applied to the facts of the case).
The particular issue in this case concerned the use of Carlsons two-factor test and his related use of visual/tactile inspection to draw conclusions on the basis of
what seemed small observational differences. We have found no indication in the record that other experts in the industry use Carlsons two-factor test or that tire experts such as Carlson normally make the very fine distinctions about, say, the symmetry of comparatively greater shoulder tread wear that were necessary, on Carlsons own theory, to support his conclusions. Nor, despite the prevalence of tire testing, does anyone refer to any articles or papers that validate Carlsons approach. Compare Bobo, Tire Flaws and Separations, in Mechanics of Pneumatic Tires 636637 (S. Clark ed. 1981); C. Schnuth et al., Compression Grooving and Rim Flange Abrasion as Indicators of Over-Deflected Operating Conditions in Tires, presented to Rubber Division of the American Chemical Society, Oct. 2124, 1997; J. Walter & R. Kiminecz, Bead Contact Pressure Measurements at the Tire-Rim Interface, presented to Society of Automotive Engineers, Feb. 2428, 1975. Indeed, no one has argued that Carlson himself, were he still working for Michelin, would have concluded in a report to his employer that a similar tire was similarly defective on grounds identical to those upon which he rested his conclusion here. Of course, Carlson himself claimed that his method was accurate, but, as we pointed out in Joiner, nothing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence that is connected to existing data only by the ipse dixit of the expert. 522 U.S., at 146.
Respondents additionally argue that the District Court too rigidly applied Dauberts criteria. They read its opinion to hold that a failure to satisfy any one of those criteria automatically renders expert testimony inadmissible. The District Courts initial opinion might have been vulnerable to a form of this argument. There, the court, after rejecting respondents claim that Carlsons testimony was exempted from Daubert-style scrutiny because it was technical analysis rather than scientific evidence, simply added that none of the four admissibility criteria outlined by the Daubert court are satisfied. 923 F. Supp., at 1522. Subsequently, however, the court granted respondents motion for reconsideration. It then explicitly recognized that the relevant reliability inquiry should be flexible,
In sum, Rule 702 grants the district judge the discretionary authority, reviewable for its abuse, to determine reliability in light of the particular facts and circumstances of the particular case. The District Court did not abuse its discretionary authority in this case. Hence, the judgment of the Court of Appeals is