* Honorable Robert B. Propst, Senior U.S. Distri ct Judge for the Northern District of Alabama, sitting by designation.

1 Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993). United States Court of Appeals,
Eleventh Circuit.

No. 96-6650. Patrick CARMICHAEL, Sr. an individual, father and next of kin to Patrick Carmichael, Jr., a minor; Luziminda Carmichael an individual, moth er and next friend of Ca rina Horn, a minor and administratrix of estates of Janice Horn; Carina Horn, a minor; Leona Carmichael, Shameela Carmichael, Natimah Carmichael, Plaintiffs-Appellants,

v. SAMYANG TIRE, INC.; Hercules Tire Company; Kuhmo, U.S.A.; Kumho & Company, Inc., Defendants-Appellees, Cooper Rubber and Tire Company, Ford Motor Company, Defendants. Dec. 23, 1997. Appeal from the United States District C ourt for the Southern District of Alabama. Before BIRCH and CARNES, Circuit Judges, and PROPST * , Senior District Judge. BIRCH, Circuit Judge: In this appeal, we determine whether the Supreme Court's Daubert 1 criteria for admission of scientific evidence should apply to testimony from a tire failure expert. In granting summary judgment against plaintiff-appellants, the district court relied on Daubert to exclude testimony from plaintiff-appellants' expert. Plaintiff-appellants, however, argue that the district court should not have applied Daubert because their expert's proffered tes timony is not "scientific." We REVERSE.
I. BACKGROUND On July 6, 1993, plaintiff-appellants, eight memb ers of the Carmichael family (collectively "the Carmichaels"), were involved in a serious automobile mishap when the right rear tire on their minivan failed. This occurrence resulted in significant trauma to each of the Carmichaels; one member of the family ultimately died from her injuries. For the purposes of this appeal, the parties agree that the failure of a tire manufactured and sold by defendant-appellees (collectively2 Carlson holds a bachelor's and a master's degr ee in mechanical engineering from the Georgia Institute of Technology. Carlson worked from 1977 to 1987 as a research engineer for Michelin Americas Research & Development, where he was involved for the majority of his tenure in tire testing. Following that experience, Carlson becam e a senior project engineer at S.E.A., Inc., where he served from 1987 to 1994 as a tire failure consultant before becoming an employee of George R. Edwards, Inc. The District Court assumed for the purpose of its Daubert analysis that Carlson is qualified to testify as an expert in tire failure analysis. See Carmichael v. Samyang Tires, Inc., 923 F.Supp. 1514, 1518-19 (S.D.Ala.1996). We, like the district court, assume that Carlson is an expert for the purposes of this appeal. "Samyang") directly caused the mishap. Following the incident, the Carmichaels subm itted the carcass of the failed tire to George Edwards, a purported expert on tire failure. After examining the tire, Edwards determined that its failure was not the result of any abuse by the Carm ichaels. Therefore, Edwards concluded that a defect in either the tire's design or its manufact ure caused the blowout. Before Edwards could be deposed by Samyang, however, he became too ill to te stify and transferred the case to his employee,
Dennis Carlson. 2 After reviewing Edwards's file on the tire and discussing the case with Edwards,
Carlson confirmed Edwards's conclusion that a de sign or manufacturing defect caused the blowout. Carlson, though, did not personally examine the ti re until approximately one hour before his deposition by Samyang, long after he had rendered hi s opinion on the cause of the blowout. In his deposition, Carlson then set forth both his analytical process and his conclusion that the
Carmichaels' tire was defective. Before the district court, Samyang moved fo r the exclusion of Carlson's testimony on the ground that it could not satisfy Daubert 's standards for reliability of scientific evidence. After reviewing Carlson's deposition, the district court agreed and excluded Carlson, writing that "none of the four admissibility criteria outlined by the Daubert court are satisfied in this case." Carmichael, 923 F.Supp. at 1521. Because the Carmichaels' only proffered evidence of a tire defect was Carlson's testimony, the district court then granted summary judgment for Samyang. See id. at 1524. The Carmichaels now appeal the exclusion of their tire expert.
II. DISCUSSION
In Daubert, the Supreme Court established several general criteria for the admission of3 Rule 702 provides that "If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to dete rmine 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."

4 The Court suggested four primary inquiries fo r determining the reliability of a scientific theory or technique: (1) whether it has been tested; (2) whether it has been subject to peer review and publication; (3) its known or potential rate of error; and (4) whether it generally accepted by the relevant scientific community. However, the Court emphasized that "[t]he inquiry envisioned by Rule 702 is ... a flexible one. Its overarching subject is the scientific validity—and thus the evidentiary relevance and reliability—of the principles that underlie a proposed submission." Daubert, 509 U.S. at 594-95, 113 S.Ct. at 2797.

5 Samyang's citations to United States v. Lee, 25 F.3d 999 (11th Cir.) (per curiam), for the contrary position are inapposite. In Lee, we examined whether a district court should apply Daubert 's reliability factors to evidence produced by machines. Id. at 998. Because the results produced by the machines were "only admissible through the testimony of an expert witness," and because "courts do not distinguish between the standards controlling admission of evidence from experts and evidence from machines," we remanded for reconsideration in light of Daubert. scientific expert testimony unde r Federal Rule of Evidence 702. 3 See Daubert, 509 U.S. at 593-95,
113 S.Ct. at 2796-98. 4 Appealing the district court's exclusion of Carlson's testimony, the Carmichaels argue that the distri ct court should not have applied Daubert 's reliability framework because Carlson is not a "scientific" expert. In response, Samyang contends that Carlson's testimony
is based on an unreliable scientific analysis. We review the distri ct court's legal decision to apply Daubert de novo, see Compton v. Subaru of Am., Inc., 82 F.3d 1513, 1517 (10th Cir.), cert. denied, --- U.S. ----, 117 S.Ct. 611, 136 L.Ed.2d 536 (1996), and its decision to exclude particular evidence
under Daubert for abuse of discretion, see General Elec. Co. v. Joiner, --- U.S. ----, --- S.Ct. ----, --- L.Ed.2d ----, (1997). Despite Samyang's protestations, "Daubert does not create a special analysis for answering questions about the admissibility of all expert testimony. Instead, it provides a method for evaluating the reliability of witnesses who claim scientific expertise." United States v. Sinclair, 74 F.3d 753, 757 (7th Cir.1996). In fact, the Supreme Court in Daubert explicitly limited its holding to cover only the "scientific context." Daubert, 509 U.S. at 590 n. 8, 113 S.Ct. at 2795 n. 8; see also United States v. Cordoba, 104 F.3d 225, 230 (9th Cir.1997) (" Daubert applies only to the admission of scientific testimony."); Compton, 82 F.3d at 1518 (same); Iacobelli Constr., Inc. v. County of Monroe, 32 F.3d 19, 25 (2d Cir.1994) (same). 5 Although the Court's analysis in Daubert mayId. at 998-99. Nowhere in Leedid we imply that Daubert applied to non-scientific expert testimony.

6 An analogy closer to the facts of the case woul d be the example of an auto mechanic and a burned-out spark plug discussed at oral argumen t. Given a proper foundation, a mechanic with years of experience with spark plugs might be able to identify for a jury burns or other marks on a spark plug that he believes disclose whether the plug burned out because normal wear or some defect; an experienced mechanic may recognize patterns of normal and abnormal wear on an auto part even though he has no knowledge of the general principles of physics or chemistry that might explain why or how a spark plug works. Such a mechanic's testimony would be non-scientific, while the testimony of another expert on the nature and effects of combustion (applied to spark plugs) would be scientific. suggest reliability issues for district courts to c onsider as they determine whether proffered evidence is sufficiently reliable for admission under Rule 702, "the trial court's role as gatekeeper is not intended to serve as a replacement for the adve rsary system: "Vigorous cross-examination, presentation of contrary evidence, and careful in struction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.' " United States v. 14.38 Acres of Land, 80 F.3d 1074, 1078 (5th Cir.1996) (quoting Daubert, 509 U.S. at 596, 113 S.Ct. at 2798). What, then, is the difference between scientific and non-scientific expert testimony? In short, a scientific expert is an expert who relies on the application of scientific principles, rather than on skill- or experience-based observation, for the basis of his opinion. See Daubert, 509 U.S. at 590, 113 S.Ct. at 2795. As the Sixth Circuit explained in Berry v. City of Detroit:
The distinction between scientific and non-scie ntific expert testimony is a critical one. By way of illustration, if one wanted to explain to a jury how a bumblebee is able to fly, an aeronautical engineer might be a helpful witn ess. Since flight principles have some universality, the expert could apply general principles to the case of the bumblebee. Conceivably, even if he had never seen a bum blebee, he still would be qualified to testify, as long as he was familiar with its component parts. On the other hand, if one wanted to prove that bumblebees always take off into the wind, a beekeeper with no scientific traini ng at all would be an acceptable witness if a proper foundation were laid for his conclusions. Th e foundation would not relate to his formal training, but to his firsthand observations. Inother words, the beekeeper does not know any more about flight principles than the jurors, but he has seen a lot more bumblebees than they have. 25 F.3d 1342, 1349-50 (6th Cir.1994); see also Sorenson v. Robert B. Miller & Assoc., Inc., Nos. 95-5085, 95-5086, 1996 WL 515351, (applying Berry). 6 Thus, the question in this case is whether Carlson's testimony is based on his application of scie ntific principles or theories (which we should7 If Carlson or the Carmichaels' counsel were to assert or imply a "scientific" basis for Carlson's testimony at trial, after representing to the district court and to this court that Carlson's opinions are "non-scientific", then we are confident that the district court will be able to take appropriate remedial measures.

8 We note that both Carlson and Samyang's expert rely on the same markings on the Carmichaels' tire for their analyses; the existence and relevance of these signs has not been questioned by either party before this court. submit to a Daubert analysis) or on his utilization of pers onal experience and skill with failed tires (which we would usually expect a district court to a llow a jury to evaluate). In other words, is the testimony at issue in this case more like that of a beekeeper applying his experience with bees or that of an aeronautical engineer appl ying his more generalized knowledge of the scientific principles of flight? Having clarified the question posed by this case, it seems apparent to us that Carlson's testimony is non-scientific. Although Samyang is no doubt correct that the laws of physics and chemistry are implicated in the failure of the Carm ichaels' tire, Carlson makes no pretense of basing his opinion on any scientific theory of physics or chemistry. 7 Instead, Carlson rests his opinion on his experience in analyzing failed tires. Afte r years of looking at the mangled carcasses of blown-out tires, Carlson claims that he can identif y telltale markings revealing whether a tire failed
because of abuse or defect. 8 Like a beekeeper who claims to have learned through years of observation that his charges always take flight into the wind, Carlson maintains that his experiences in analyzing tires have taught him what "bead gr ooves" and "sidewall deterioration" indicate as to the cause of a tire's failure. Indeed, Carlson a sserts no knowledge of the physics or chemistry that might explain why the Carmichaels' tire failed. Thus, we conclude that Carlson's testimony falls outside the scope of Daubert and that the district court erred as a matter of law by applying Daubert
in this case. Still, the inapplicability of Daubert should not end the day regarding Carlson's reliability. Under Rule 702, it is the district court's duty to determine if Carlson's testimony is sufficiently reliable and relevant to assist a jury. See 14.38 Acres, 80 F.3d at 1078. Moreover, Carlson's testimony is subject to exclusion under Federal Rule of Evidence 403 if its probative value is9 After analyzing Carlson's proffered testimony under Daubert, the district court concluded that "Carlson's testimony is simply too unreliable, too speculative, and too attenuated to the scientific knowledge on which it is based to be of material assistance to the trier of fact...." See Carmichael, 923 F.Supp. at 1522. Even without requiring Carlson's testimony to satisfy the Daubert criteria on remand, the district court still may find that, under all the circumstances, Carlson's testimony is so unreliable as to be unhelpful to the jury. We do not intend our comments regarding Carlson's testimony or qualifications to constrain the district court's discretion to admit or exclude his testimony under the proper Rule 702 or Rule 403 standards.

10 We note that many of Samyang's criticisms of Carlson may also apply to the qualification of Samyang's own tire failure expert. However, we leave such issues for the district court to consider on remand. substantially outweighed by its likely prejudicial effect. 9 Aside from its Daubert related arguments, Samyang has presented this court with a number of potentially troubling criticisms of Carlson's alleged expertise and methodology, including his rendering of an opi nion regarding the Carmichaels' tire before he had personally inspected its carcass. 10 We leave judgments about such matters to the
discretion of the district court on remand.
III. CONCLUSION The district court erred as a matter of law in applying the Daubert criteria to the Carmichaels' proffered expert testimony. Therefore, we REVE RSE and REMAND the case to the district court for further proceedings consistent with this opinion.