Full opinion text
MEMORANDUM DAVIS, District Judge. Contents I.INTRODUCTION.386 II.FACTS AND PROCEDURAL HISTORY.386 III.DR. JOSEPH SHELLY IS NOT A QUALIFIED EXPERT UNDER THE CIRCUMSTANCES OF THIS CASE, AND HIS OPINION TESTIMONY IS NOT ADMISSIBLE BECAUSE HIS OPINIONS WERE NOT RELIABLY DERIVED FROM SOUND SCIENTIFIC OR ENGINEERING METHODOLOGIES; NO SUCH INFIRMITIES APPLY TO THE DEFENDANTS’ EXPERTS.390 A. Dr. Shelly Lacks Relevant Qualifications Under the Circumstances of this Case.391 B. Although Dr. Shelly Has Identified Valid Scientific/Technical Methodologies and Has Applied Appropriate Labels to his Analytical Protocol, He Failed to Employ those Methodologies in a Scientifically or Technically Valid Manner and Has Therefore Failed to Derive Reliable and Valid Engineering Conclusions.394 1. Dr. Shelly’s Causation Opinions Do Not Reliably Arise From His Fault Tree Analysis.395 2. Dr. Shelly’s Opinions As To The Discharge Chute Do Not Reliably Arise From A Valid “Risk Utility Analysis”.400 3. Dr. Shelly’s Opinions About Adequacy of Warnings Are Not Admissible.402 C. Defendants’ Experts Are Qualified and to the Extent Their Opinions May Be Relevant, They Are Admissible.403 IV. DEFENDANTS ARE ENTITLED TO JUDGMENT AS A MATTER OF LAW AS TO ALL THEORIES EXCEPT STRICT LIABILITY BASED ON DESIGN DEFECT AND IMPLIED WARRANTY OF MERCHANTABILITY; PLAINTIFFS ARE NOT ENTITLED TO SUMMARY JUDGMENT AS TO ANY THEORY.405 A. Summary Judgment Standards.405 B. Strict Liability Claims.406 1. Manufacturing Defect Claim.410 2. Failure to Warn Claim.413 3. Design Defect Claim .415 C. Maryland Consumer Protection Act Claim.416 D. Breach of Warranty Claims.420 1. Express Warranty Claim.420 2. Implied Warranty of Merchantability Claim.421 E. Loss of Consortium.422 V. MOTION TO AMEND AND RELATED MOTIONS. 422 VI. CONCLUSION. 424 This is a personal injury damages action based on Maryland products liability law. It is a unique case in that the claims arise out an alleged defect which disabled the very safety apparatus — a form of “dead man” lever — that was designed into the product — a snow thrower — as a result, in part, of prior products liability claims. The particular alleged failure of the safety feature had never been reported in a prior accident and the alleged failure never has been replicated, in either a controlled experiment or in the ordinary use of any snow thrower. “[Sjometimes truth is stranger than fiction.” It will fall to the jury to determine whether that venerable maxim applies in this case. I. INTRODUCTION The case is here on the basis of diversity of citizenship jurisdiction; it was instituted by James and Nancy Shreve in state court and timely removed by defendants. The Shreves seek damages for injuries James Shreve (hereinafter “Shreve”) suffered while he used a Craftsman brand snow thrower, and for loss of consortium. Defendants are Sears, Roebuck and Company, from whom Shreve purchased the snow thrower, and Murray, Inc., the manufacturer of the snow thrower. Discovery has concluded and now pending are the following motions: (1) defendants’ motion to exclude the testimony of the Shreves’ expert witness; (2) the Shreves’ reciprocal motion to exclude the testimony of the defendants’ experts; (3) the parties’ cross-motions for summary judgment; (4) the Shreves’ motion to file a second amended complaint (and certain discovery-related motions arising therefrom); and (5) the Shreves’ motions to compel. The motions have been fully briefed and a hearing has been held, during which I examined the snow thrower with counsel. For the reasons set forth in Part III below, defendants’ motion to exclude the testimony of the Shreves’ expert shall be granted; the Shreves’ reciprocal motion to exclude the testimony of the defendants’ experts shall be denied. In Part IV below, I explain why defendants’ motion for summary judgment shall be granted in part and denied in part, and the Shreves’ motion for summary judgment denied. In the circumstances of this case, as defendants largely concede, even without their expert witness, the plaintiffs may nonetheless present their strict liability design defect claim, as well as their implied warranty claim, to the jury. In Part V below, I explain why I shall deny plaintiffs’ motion to amend and the discovery motions, including the motions to compel. II. FACTS AND PROCEDURAL HISTORY Shreve is 56 years old and has been employed as a carpentry foreman for 32 years. He is right-handed. He has continued to work as a carpentry foreman since the events at issue in this case on the same terms as prior to the accident, but he experiences trouble completing carpentry tasks and other tasks of daily life. On September 20, 1997, Shreve purchased a Craftsman brand snow thrower from Sears at a store in Baltimore County. The snow thrower was manufactured by Murray. The snow thrower is a walk behind, self propelled snow thrower with an eight horsepower gasoline engine. It is equipped with an electric/recoil start system, six forward and two reverse speeds controlled by a speed shift lever, and a throttle to control fuel feed. The snow thrower is designed to remove snow from ground surfaces. It has a wide, rotating screw auger at the front that is geared to high speed rotating impeller blades. As the snow thrower is advanced into accumulated snow, the auger gathers the snow and forces it into the impeller blade chamber. The four impeller blades then capture the snow and thrust it out a vertical discharge chute. This chute has an adjustable deflector plate, and the entire discharge chute can be adjusted so that snow can be thrown to either side of the machine. The motor will not turn on unless the ignition key is in place. The output shaft of the engine is fitted with two belt pulleys. One belt drives the road wheels. The second belt drives a shaft on which is mounted the impeller and a gear that drives the auger. The snow thrower is equipped with continuous activation engagement controls for both the traction and auger/impeller drives (hereinafter “dead man” controls or levers). Power to both of these mechanical drives is interrupted when the operator releases the “dead man” controls. A braking mechanism is also applied to the auger/impeller when the auger/impeller control is released. These levers are spring mounted on the handle bar of the snow thrower and are designed to be depressed when the person operating the machine is in the safest position for operation. In the idling position, the belt between the pulleys is slack and so is not turned by the drive pulley. When the “dead man” levers are depressed, they engage the idler pulley against the drive belt, which tightens the belt and causes it to have traction against the drive pulley and to turn. The lever on the left hand side of the handle bar controls the machine’s traction drive. The lever on the right hand side controls the auger drive. The auger and impeller blades grind the snow, and the impeller blades force the snow up through the discharge chute, expelling the snow from the machine. The discharge chute is located above the impeller blades and, as mentioned above, it can be adjusted to point either to the left or to the right, depending on the direction in which the operator wants to expel the snow. The chute is spherical and approximately six to ten inches in diameter. It is not fully enclosed but is open on one side. At the time it was manufactured and at the time Shreve purchased it, the snow thrower conformed to all applicable industry standards (and it so conforms today). Shreve purchased the snow thrower for home use. He had not previously owned or used a snow thrower. The snow thrower came fully assembled. It was accompanied by an Owner’s Operating Manual. Before he used the snow thrower, Shreve read the Owner’s Manual, and he understood its contents. The Manual contained warnings not to make any adjustments to the snow thrower when the motor is running and to stop the motor whenever leaving the operator’s position or when unclogging the auger or the impeller. The snow thrower also has a decal on the machine warning that the engine should be turned off before attempting to unclog the discharge chute. A second decal warns the operator to read the Owner’s Manual before using the machine and that the engine should be turned off prior to unclogging the chute or leaving the machine for any reason. Shreve read and understood the warning decals on the machine. Shreve understood how the machine functioned, as he regularly operated power equipment at his carpentry foreman job. Shreve used the snow thrower approximately two or three times prior to March 9, 1999. His son, Michael Shreve, also used it once. Shreve did not use the snow thrower during the winter of 1997-98. Shreve claims that his son told him that when his son used the snow thrower, he had had difficulty getting the machine out of reverse and that it “looked like ice or something had built up on the throttle at the bottom of it.” Shreve Dep. at 19. Shreve took no action in response to this problem, and he never reported experiencing it or witnessing it himself. Shreve experienced no problems with the machine, which was not altered or repaired at any time after he purchased it. The snow thrower was always stored in a shed behind the Shreves’ home, which is located at the southwest corner of Linda Drive and Ingleside Avenue in Catonsville, Maryland. Linda Drive runs east/west; it slopes upwards as it goes east. Ingleside runs north/south. Shreve testified on deposition on October 3, 2000, and described the accident, to which there were no eyewitnesses. Shreve testified that he began using the snow thrower at about 3:00 p.m. on March 9, 1999, after returning home from work. It had been snowing all day and was still snowing when he began. Approximately five inches of snow had already accumulated on the ground. Shreve first used the snow thrower to clear the sidewalk on Linda Drive, clearing approximately 200 to 300 feet. Shreve Dep. at 36. He cleared the sidewalk going east and up the slope of Linda Drive towards Ingleside. Shreve Dep. at 36. After clearing the sidewalk, Shreve placed the snow thrower in the street, next to the curb on Linda Drive. The front of the machine was facing west down Linda Drive. He was going to next clear portions of Linda Drive. The discharge chute was pointing towards the street. Shreve decided to get his gloves because his hands were cold. His gloves were in his pickup truck, which was parked on Linda Drive, about 30 feet west from where he left the snow thrower. Shreve did not turn off the motor when he walked away from the thrower to get his gloves from his truck. Shreve Dep. at 38., When he left the machine, he necessarily released the auger/impeller drive and traction drive “dead man” levers. Shreve Dep. at 51. Shreve retrieved his gloves and then walked up the slope of Linda Drive east towards the snow thrower. He was walking in the street. As he got near the machine, Shreve lost his balance and began to fall. As he fell, his right hand went into the chute deflector of the snow thrower. Shreve Dep. at 41. His right hand came into contact with the rotating impeller blades, resulting in the loss of parts of the three middle fingers on his right hand. Shreve does not remember whether he saw the auger blades rotating as he was walking up the street towards the machine or when he was falling. Shreve Dep. at 45. He believed that they were not rotating when he was walking towards the machine because he had released the “dead man” lever. Shreve Dep. at 52. Shreve remembered losing his balance, falling, and putting his hands out to catch himself. Shreve Dep. at 50. He did not remember hitting the ground or that any other portion of his body, besides his right hand, touched any part of the snow thrower. Shreve Dep. at 50. In connection with the summary judgment motions, Shreve submitted an affidavit with significantly more detailed information about the accident and its potential causes. In this affidavit, Shreve stated that he did not depress the auger/impeller “dead man” lever with his left hand or with any other part of his body as he was falling. Shreve Affidavit ¶ 7. He stated that the impeller was rotating when his arm went into the chute. Id. Shreve’s middle three fingers were amputated by the blades and his pinky finger was injured and required a tissue graft and short arm cast. The Shreves retained Dr. Joseph Shelley as an expert witness. On September 5, 2000, Dr. Shelley submitted his “Engineering Analysis of the Safety Guarding on the Craftsman Model Number 536.886180 Snow Thrower in the Injury Incident Involving James A. Shreve.” In describing the incident, this report located Shreve on the sidewalk of one of the streets adjacent to his house (not in the street), with the snow thrower in the street with its auger blades facing him as he approached it from his truck and the discharge chute pointing toward the sidewalk. Dr. Shelly’s report concludes that “more likely than not” the accident was caused by a design defect whereby water accumulated in the groove in the underside of the driven pulley, which controlled the “dead man” levers, and froze, thereby forming ice and preventing the levers from disengaging the auger/impeller blades. Thus, according to Dr. Shelly, when Shreve lost his footing and fell next to the snow thrower and his right hand went into the discharge chute, the impeller blades “had some rotational motion inside the impeller chamber” and severed his fingers. Sept. 5, 2000 Report at 16. Dr. Shelley stated that the driven pulley of the auger/impeller belt drive “shows a heavily rusted condition. It may be concluded from this appearance that the pulley had been operated in a wet environment. Such a pulley surface condition would be consistent with melted snow water running on to, and over, this pulley.” Id. at 20. The Shelly report also concludes that the lack of “adequate guarding of the shear points of the impeller blade tip edges, in the form of an enclosing tube directly above the impeller housing, is a critically serious design defect.” Id. at 17. He opined that [a] diverging, fully enclosed extension tube should have been provided above the exit opening from the impeller blade chamber. Such an enclosed discharge duct would have virtually no effect on the throwing of snow through it, and it would have provided an order-of-magnitude increase in protection from injury due to inadvertent contact with the moving impeller blades. The technology for the design, and fabrication, of such an enclosed chute was well known, and widely available, at the time of manufacture of the snow thrower. Id. The Shelly report identifies three other “serious design defects:” “[1] The lack of any safety warnings in the manual on the danger of losing one’s footing near the snow thrower, and making inadvertent contact with the exposed impeller blades; [2] The lack of any reference in the trouble shooting section of the manual to the problem of failure to obtain complete clutch disengagement when the [dead man] levers are released; [and 3] The lack of any safety warning labels on the snow thrower describing the danger of losing one’s footing near the snow thrower and making inadvertent contact with the exposed impeller blades.” Id. at 18,19 (deletions omitted). On September 16, 2000, Dr. Shelley submitted his first supplementary report, in which he disclosed that the U.S. Weather Service Meteorological/Climatological weather record for nearby Anne Arundel County for the date of the accident indicated that five inches of a mixture of snow, ice pellets, and ice had fallen. Also, the air temperature that day ranged from 24 to 28 degrees Fahrenheit. Shreve Opp. Ex F. Defense experts Raymond Elmy and David Sassaman submitted reports dated November 1, 2000, and October 16, 2000, respectively. Those reports state the following obvious conclusion: had Shreve followed the operating manual safety rules and turned off the motor while leaving it unattended to retrieve his gloves, Shreve would not have sustained injury. Sassa-man Report at 10; Elmy Report at 6. They each also conclude that Dr. Shelley’s theory of ice build-up in the groove in the driven pulley has never been documented by anyone and that such an occurrence is impossible. Sassaman’s report states that “in the entire history of this machine, along with all expert testing, there has not been a single report of the operator presence control failing to stop the auger/impeller.” Id. His report concludes that given the nature of Shreve’s injury, it “[must have] occurred while the mechanism was under full power and not idling or free wheeling.” Id. at 10. Moreover, Sassaman stated that Dr. Shelley’s idea that an enclosed flared discharge chute would improve safety was misguided because it would promote chute clogs and be more dangerous. Id. at 11. He reported that his inspection of Shreve’s snow thrower did not reveal evidence of a leak path for snow melt to reach the pulley, and that in any event the belt pulley system of the machine generates heat that would prevent any water from freezing. Thus, he offered the opinion that “it is not possible for water to accumulate and freeze in the lower pulley and cause a malfunction of the auger/impeller clutch/ brake mechanism in this machine.” Id. at 12. Dr. Shelley reviewed the defense expert reports and submitted a second supplemental report on or about November 18, 2000. He responded to their reports point by point. He reiterated that it was a design defect not to include an enclosed discharge chute, even though no snow thrower manufacturer used that design. Shreve Opp. Ex G. The deadline for submitting Rule 26(e)(2) supplemental expert disclosures was November 30, 2000. In a December 6, 2000, letter, Dr. Shelley reported that he had researched industry practice concerning discharge chutes on snow throwers and that he had found three models of Toro brand snow throwers that used an “m wire” guard across the discharge chute opening. The letter concluded that “[t]he use of a formed wire chute guard would have been a viable alternative to use of an enclosed, flaring discharge chute.” Shreve Opp. Ex. H. III. DR. JOSEPH SHELLY IS NOT A QUALIFIED EXPERT UNDER THE CIRCUMSTANCES OF THIS CASE, AND HIS OPINION TESTIMONY IS NOT ADMISSIBLE BECAUSE HIS OPINIONS WERE NOT RELIABLY DERIVED FROM SOUND SCIENTIFIC OR ENGINEERING METHODOLOGIES; NO SUCH INFIRMITIES APPLY TO THE DEFENDANTS’ EXPERTS I shall first consider the cross-motions to exclude expert witness testimony, each side seeking to exclude the experts of the other. As amended effective December 1, 2000, Rule 702 of the Federal Rules of Evidence states: 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, 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. The “basic gatekeeping obligation” previously identified by the Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993), and now embraced by Rule 702 applies not only to “scientific” testimony, but to all expert testimony. Kumho Tire Co. v. Carmichael, 526 U.S. 137, 147, 119 S.Ct. 1167, 143 L.Ed.2d 238 (1999). Indeed, as the Supreme Court has explained, “no clear line” divides “ ‘scientific’ knowledge and ‘technical’ or ‘other specialized’ knowledge. Disciplines such as engineering rest upon scientific knowledge.” Id. at 148, 119 S.Ct. 1167. The gatekeeping function, like other determinations of admissibility of evidence, requires the trial judge to exercise an informed and broad discretion. Cooper v. Smith & Nephew, Inc., 259 F.3d 194, 199-200 (4th Cir.2001); Oglesby v. General Motors Corp., 190 F.3d 244, 250 (4th Cir.1999); cf. F.R. E.104(a). Two aspects of this determination are pertinent to the case at bar: whether the expert is qualified, and if so, whether the opinion he proffers is reliable. See Kumho Tire, 526 U.S. at 150, 153, 119 S.Ct. 1167. I am constrained to conclude that, as to Dr. Joseph Shelly, the answer to each of these inquiries is “no.” A. Dr. Shelly Lacks Relevant Qualifications Under the Circumstances of this Case “[T]here are many different kinds of experts, and many different kinds of expertise.” Kumho Tire, 526 U.S. at 150, 119 S.Ct. 1167. The fact that a proposed witness is an expert in one area, does not ipso facto qualify him to testify as an expert in all related areas. See, e.g., Oglesby, 190 F.3d at 247; Wilson v. Woods, 163 F.3d 935, 938 (5th Cir.1999); Ancho v. Pentek Corp., 157 F.3d 512, 517 (7th Cir.1998); Bogosian v. Mercedes-Benz of North America, 104 F.3d 472, 476 (1st Cir.1997); Trumps v. Toastmaster, Inc., 969 F.Supp. 247, 252 (S.D.N.Y.1997); Silva v. American Airlines, Inc., 960 F.Supp. 528, 531 (D.P.R.1997); Diviero v. Uniroyal Goodrich Tire Co., 919 F.Supp. 1353, 1356-57 (D.Ariz.1996), aff'd, 114 F.3d 851 (9th Cir.1997). More specifically, an expert who is a mechanical engineer is not necessarily qualified to testify as an expert on any issue within the vast field of mechanical engineering. Unless he is to testify only to general engineering principles that any mechanical engineer would know, the engineer must possess “some special skill, knowledge or experience,” Ancho, 157 F.3d at 517, concerning the particular issue before the court. Compare Oglesby, 190 F.3d at 247 (testimony excluded of well-qualified mechanical engineer with no specialized experience or expertise in evaluating either automobile manufacturing processes or the strength of plastic automobile component parts); Wilson, 163 F.3d at 938 (recognized expert on causes of fires excluded as expert on motor vehicle collision accident reconstruction); Ancho, 157 F.3d at 517 (mechanical engineer with no experience designing or evaluating factories not an expert on industrial plant configuration); Bogosian, 104 F.3d at 477 (well qualified master auto mechanic was not qualified as expert on car design absent relevant experience or knowledge); Trumps, 969 F.Supp. at 252 (board certified safety professional and mechanical engineer not qualified to offer expert testimony regarding malfunction of electric grill; electrical engineering outside expert’s field); Silva, 960 F.Supp. at 531(civil engineer with public works experience could not testify about safety aspects of aircraft design about which he had no professional experience); Diviero, 919 F.Supp. at 1356-57 (engineer with over 30 years experience working with bias belted tires not qualified to testify that steel belted tire was unreasonably dangerous because two tires significantly different and he lacked chemical background to gauge compatibility of steel and rubber interface in tire), with Wheeler v. John Deere Co., 935 F.2d 1090, 1100 (10th Cir.1991) (mechanical engineer with special expertise in safe design of farm equipment could testify that combine was dangerous beyond the expectation of the ordinary consumer because inherent in design of safety mechanisms is anticipation of how such equipment will be perceived and used by consumers); Williams v. Pro-Tec, Inc., 908 F.2d 345, 348 (8th Cir.1990)(mechanical engineer who had conducted tests to determine the amount of force with which a racquetball could strike the human eye when the ball was shot at various speeds at a person wearing the Pro-Tec eye-guard could testify that the eye guard would slow the ball and was not unreasonably dangerous despite lack of expertise in ophthalmology); Lavespere v. Niagara Machine & Tool Works, Inc., 910 F.2d 167, 176 (5th Cir.1990) (professor of mechanical and production engineering allowed to testify about designing point-of-operation safeguards for press brake industry though he had never designed a press brake or safeguards for that device because he had practical experience designing similar devices, was a recognized expert on similar devices and he had conducted a review of the relevant literature), cert. denied, 510 U.S. 859, 114 S.Ct. 171, 126 L.Ed.2d 131 (1993), abrogated in part on other grounds, Little v. Liquid Air Corp., 37 F.3d 1069 (5th Cir.1994). While the fit between an expert’s specialized knowledge and experience and the issues before the court need not be exact, see Wheeler, 935 F.2d at 1101 (lack of perfect fit will go to the weight not the admissibility of expert testimony), an expert’s opinion is helpful to the trier of fact, and therefore relevant under Rule 702, “only to the extent the expert draws on some special skill, knowledge or experience to fonnulate that opinion; the opinion must be an expert opinion (that is, an opinion informed by the witness’ expertise) rather than simply an opinion broached by a purported expert.” Ancho, 157 F.3d at 518 (internal quotations omitted)(quoting United States v. Benson, 941 F.2d 598, 604 (7th Cir.1991)). As Daubert and Kumho Tire make clear, “the [trial court’s] gatek-eeping inquiry must [therefore] be ‘tied to the facts’ [and issues] of the particular ‘case.’ ” Kumho Tire, 526 U.S. at 150, 119 5.Ct. 1167 (quoting Daubert, 509 U.S. at 591, 113 S.Ct. 2786). Applying the above principles to the case at hand, I conclude that while Dr. Shelley is an expert as to many things, he does not qualify as an expert on the safe design and operation of snow throwers. The Shreves seek to have Dr. Shelley testify as an expert to “two primary opinions in this litigation:” First, Dr. Shelley opined that the origin of one product defect at issue was a design that allows the freezing, and building-up, of melted snow in the Snow Thrower’s auger/impeller driven pulley groove (thus increasing the effective diameter of that pulley groove) .... Dr. Shelley’s second primary opinion is that the Snow Thrower suffered a design defect by not having a component to guard or shield the opening above the impeller blade that amputated Mr. Shreve’s finger (whether that component be a “flared chute,” or the conceptually identical m-wire (such as the Toro M-wire)). Shreve Opp. to Defs’. Mot. to Exc. p. 3 n. 4. Dr. Shelley also offered an opinion that the subject snow thrower’s warnings were inadequate and what adequate warnings for this product would be. Dr. Shelley is an eminently qualified mechanical engineer and professor of mechanical engineering whose courses include Machine Design and Mechanical System Failure Analysis. Aside from testifying as an expert (see infra note 7), however, he has had no professional experience with respect to the design, manufacture, operation, or safety of outdoor power equipment, including snow throwers. Dr. Shelley did not conduct a review of the literature on snow throwers. He has never been involved with any industry or governmental body charged with the responsibility of developing or overseeing safety standards for snow throwers or any similar device. He has never owned and, outside the context of litigation, has never operated a snow thrower. His sole exposure to the specific type of snow thrower at issue in this case is the hour and one-half that he spent on August 8, 2000, at the Shreves’ residence. On that occasion, he operated the snow thrower for three minutes in summer conditions. But for three litigation matters, including this one, he would never have laid a hand on a snow thrower. Dr. Shelley is clearly an experienced expert witness. His resume lists close to 200 “product liability” reports he authored as of December 1998. In these reports, he analyzed the design and alleged defects of products that caused accidents as varied as ladders and step stools, trucks, saws, lawn mowers, staplers, chaise lounges, folding chairs, bulk mail sorters, packaging machines, walkers, clothes hooks, exercise machines, stone crushers, debris chippers, presses, dough slicing machines, concrete mixing trucks, and more. He has even prepared two other reports concerning injuries caused by snow throwers. See supra note 7. But one does not necessarily become an expert on a topic simply by testifying about it in court. “Although [Dr. Shelly’s] background might permit him to learn faster than others about the design and safety aspects of [snow throwers], an expert must have specific knowledge, not mere capacity to acquire knowledge.” Silva, 960 F.Supp. at 531. In my judgment, Dr. Shelley offers his opinions concerning the Murray snow thrower at issue in this case as a classic “hired gun,” with no particular expertise concerning snow throwers. B. Although Dr. Shelly Has Identified Valid Scientific/Technical Methodologies and Has Applied Appropriate Labels to his Analytical Protocol, He Failed to Employ those Methodologies in a Scientifically or Technically Valid Manner and Has Therefore Failed to Derive Reliable and Valid Engineering Conclusions Even were I to deem Dr. Shelley to be qualified to offer expert opinion testimony concerning the design and operation of snow throwers, nevertheless, his particular implementation of the methodology he identified by which he arrived at his opinions lacks scientific or technological validity in the field of engineering; thus, he has fatally undermined the soundness of his methodology. Consequently, his opinions are unreliable and inadmissible. See Kumho Tire, 526 U.S. at 153, 119 S.Ct. 1167 (determining that a well qualified mechanical engineer’s testimony was properly excluded because his methodology was not scientifically or technologically valid). Under Rule 702, “the trial judge must ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable.” Daubert, 509 U.S. at 589, 113 S.Ct. 2786. In Daubert, the Supreme Court laid out five non-exhaustive factors that a court may consider in determining whether to admit an expert opinion as rehable, including: -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 technique’s operation”; and -Wlhether the theory or technique enjoys “general acceptance” within a “ ‘relevant scientific community.’ ” Kumho Tire, 526 U.S. at 149-150, 119 S.Ct. 1167 (quoting Daubert, 509 U.S. at 592-94, 113 S.Ct. 2786). The Daubert factors “are meant to be helpful, not definitive,” id. at 151, 119 S.Ct. 1167, and “the court’s evaluation is always a flexible one.” Oglesby, 190 F.3d at 250. As the Supreme Court held in Kumho Tire, “[i]ndeed, those 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 149, 119 S.Ct. 1167. The inquiry underlying the Daubert factors involves not only whether the methodology that the expert used is generally accepted within the relevant scientific or professional community, but also whether it was reasonable for the expert to use that methodology to “draw a conclusion regarding the particular matter to which the expert testimony is directly relevant.” Id. at 154, 113 S.Ct. 2786. As the Fourth Circuit explained in Oglesby, “[a] reliable expert opinion must be based on scientific, technical or other specialized knoivledge and not on belief or speculation, and inferences must be derived using scientific or other valid methods.” 190 F.3d at 250 (emphasis in original)(citing Daubert, 509 U.S. at 592-93, 113 S.Ct. 2786). “[T]o qualify as ‘scientific knowledge,’ an inference or assertion must be derived by the scientific method. Proposed 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. 2786. “Scientific methodology today is based on generating hypotheses and testing them to see if they can be falsified .... The statements constituting a scienti fie explanation must be capable of empirical test.” Id. at 593, 113 S.Ct. 2786 (citations omitted). 1. Dr. Shelly’s Causation Opinions Do Not Reliably Arise From His Fault Tree Analysis Dr. Shelley purports to rely upon “fault tree analysis” to arrive at his opinion that Shreve was injured as a result of water from melted snow invading the underside groove of the driven pulley, freezing in the groove, and thereby causing the radius of the pulley to expand. The increased radius of the driven pulley caused the belt to remain taut (rather than appropriately slack) when Shreve released the “dead man” lever, which in turn caused the auger and impeller blades to continue rotating even when Shreve was not depressing the “dead man” levers. Dr. Shelley testified that his visual inspection of the driven pulley shaft revealed rust, indicating the presence of water. However, he never tested his hypothesis by using Shreve’s snow thrower (or any snow thrower) under climatic conditions similar to (or different from) those in which Shreve’s accident occurred. His only “test” of the snow thrower, a three minute operation of it at the Shreves’ home in Maryland in August, revealed that the machine operated properly. “Fault tree analysis” is a method used “primarily as a design tool for engineers.” Doblar v. Unverferth Mfg. Co., 981 F.Supp. 1284, 1287 (D.S.D.1997), withdrawn and sanctions imposed upon the expert mechanical engineer, 185 F.R.D. 258 (D.S.D.1999). As Dr. Shelley explained: The term “fault tree analysis” is widely used in the defense industry to analyze complex weapons systems. It is a simple concept, using a top-to-bottom identification of all possible failure/hazard modes of a system. It can be envisioned as an inverted tree. You start at the trunk and flow down through each of the branches (each branch representing a subsystem). I used this term at the deposition only because of my long association with weapons systems during 29 years as a consultant to the army. In the case of an elementary mechanical system such as a snow thrower, the concept would be to simply identify all hazards to users of this product, so that these hazards could be eliminated in the design. This is the benchmark standard approach in mechanical engineering design with products that can cause injury to persons. Shelley Aff. at 2-3. Dr. Shelley allegedly used fault tree analysis to conclude that ice in the groove on the underside of the pulley caused the “dead man” levers to malfunction, allowing the auger/impeller blades to rotate when Shreve was not depressing the levers, thus causing the amputation of his fingers. The evidence in the record exposes two serious flaws in Dr. Shelly’s methodology. First, a legitimate fault tree analysis requires consideration of all potential causes of an accident, including human error. Dr. Shelley’s fault tree analysis, however, does not consider any possibility of human error contributing to Shreve’s accident. When asked whether he considered the possibility that Shreve could have accidentally depressed the “dead man” lever with his left hand as he grasped to break his fall, Dr. Shelley replied, “No, not at all.” Shelley Dep. at 124-29, 150. Dr. Shelly did not consider this possibility even though he acknowledged that it was indeed a possible explanation for the accident. Id. at 127. Significantly, the only testimony from Shreve at the time of Dr. Shelly’s work on the case indicated that Shreve could not remember how his fall happened or where his hands were when he fell. Id. at 128. Neither did Dr. Shelley consider whether Shreve had tied down the “dead man” control, whether another person was depressing the “dead man” control, or whether Shreve himself was depressing the “dead man” control while he inserted his right hand into the discharge chute. Dr. Shelley’s ostensible fault tree analysis likewise does not encompass the possibility that had Shreve extinguished the motor of the snow thrower before leaving it unattended, as the Owner’s Manual instructed, the accident would not have happened. It would seem reasonable to include such potential human errors, e. g., leaving the motor running, as a potential cause of the accident, if indeed a fault tree analysis was the methodology employed. Dr. Shelly’s failure to do so seriously undermines the validity of his fault tree analysis. See Cooper, 259 F.3d at 202 (“[I]f an expert utterly fails to consider alternative causes or fails to offer an explanation for why the proffered alternative cause was not the sole cause, a district court is justified in excluding the expert’s testimony.”). At bottom, Dr. Shelly’s knowing disregard of human factors in his analysis constitutes a serious deficiency in his ostensible fault tree analysis as “assessments of the causes of events are inevitably influenced by the array of possible causes that are made salient to them.” Allen v. Chance Mfg. Co., Inc., 873 F.2d 465, 470 & n. 5 (1st Cir.1989) (citing Fischheff, Slovic & Lichtenstein, Fault Trees: Sensitivity of Estimated Failure Probabilities to Problem Representation, 4 J. Experimental Psy-chol.: Human Perception & Performance 330 (1978)). In sum, it is clear that Dr. Shelley did not perform an objective fault tree analysis as would a disinterested professional applying that analytical tool to discover how best to design a safe snow thrower after an injury-causing incident. See Cooper, 259 F.3d at 203 (“Kumho Tire emphasizes that the purpose of Rule 702’s gatekeeping function is to make ‘certain that an expert ... employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the field.’ ”). Rather, the conclusion is inescapable that to arrive at his opinion as to the cause of the accident, Dr. Shelly assumed that human error could not have played a role in the accident, relied upon his professional knowledge of mechanical systems to hypothesize about what theoretical possibilities inhered in the design of the snow thrower to support the (theoretically possible) manner of the alleged malfunction, and he then developed a seemingly plausible hypothesis — ice build-up in the groove of the.underside of the driven pulley — to conform to the mechanical components present in the snow thrower. The second major fault with Dr. Shelley’s use of fault tree analysis to formulate an opinion about the cause of the accident is inextricably bound up with the first. That is, even if Ms hypothesis about a mechanical malfunction caused by ice build-up is sound, it was never tested. Engineering is a field of applied science. Kumho Tire, 526 U.S. at 148, 119 S.Ct. 1167. It relies on scientific method. That method involves formulating a hypothesis to explain the world based upon what is already known and then subjecting the hypothesis to tests designed to falsify (or confirm) the hypothesis. See Daubert, 509 U.S. at 590, 113 S.Ct. 2786. Dr. Shelley acknowledged that engineers use fault tree analysis to take into account potential risks in the formulation of designs. Shelley Dep. at 123. Essentially, fault tree analysis determines a design option (or options) that the engineer hypothesizes minimizes the anticipated risk. Before that design is adopted by a manufacturer, however, the hypothesis is tested. In Dr. Shelley’s words, “this is what engineers do, they use basic bodies of engineering knowledge, and they come up with designs. They don’t build everything first. Then they can build it and test it.” Shelley Dep. at 123. Contrary to his own understanding of the proper approach, Dr. Shelley never bothered to test his hypothesis that ice buildup in the groove of the driven pulley increased the radius of the pulley. Equally inexplicable (and equally inexcusable) Dr. Shelly never tested the overarching major premise of his causation syllogism: that the quantum of heat generated by the v-belt and/or present within the engine compartment of the snow thrower was such as to permit moisture to freeze in the groove on the underside of the driven pulley. Shelley Dep. at 141. To his knowledge, neither his ice build-up theory, nor anything like it, has ever been verified in any other way or in any other context, as it is not described in any literature with which he is familiar. Defendants’ experts, who I find are fully qualified in the relevant field of snow thrower design, manufacture and use, assert that the ice build-up hypothesis is essentially specious. In short, Dr. Shelley arrived at his opinion that ice build-up in the groove on the underside of the driven pulley caused Shreve’s fingers to be amputated by applying a methodology that is the opposite of the scientific method. It appears that he posited a seemingly plausible mechanical defect, and an etiology for it that is grounded in unexceptional laws of physics and chemistry (e. g., snow melts; moisture creates rust in some metals) and unexamined assumptions (e. g., no human error contributed to the incident), to explain Shreve’s accident, after refusing to consider any other possible explanations. Then, he concluded that his hypothetical cause was “more likely than not” true without any attempt to verify or falsify it. Plainly, Dr. Shelley’s theory was capable of being tested, but it was not. Although the technique of fault tree analysis is relied upon within the engineering community for certain purposes, there has been no showing that Dr. Shelly’s use of that label to describe his work in this case mimics the work of systems designers who employ that technique in the real world. Reliability is plainly lacking here. See Kumho Tire, 526 U.S. at 149-50, 119 S.Ct. 1167 (citing Daubert, 509 U.S. at 592-94, 113 S.Ct. 2786). Dr. Shelley attempted to justify his methodology by explaining that the snow thrower is a simple machine, implying that verification was not needed. That may be an opinion, but it is not a scientific opinion, or an opinion supported by appropriate validation; rather, it is merely Dr. Shelly’s subjective opinion. Cf. id., 526 U.S. at 157, 119 S.Ct. 1167 (stating that “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” (internal quotation marks omit-ted)(quoting General Electric v. Joiner, 522 U.S. 136, 146, 118 S.Ct. 512, 139 L.Ed.2d 508 (1997))).- The Fourth Circuit does not accept opinions from experts simply because the “expert says it is so.” Alevromagiros v. Hechinger Co., 993 F.2d 417, 421 (4th Cir.1993) (quoting Viterbo v. Dow Chemical Co., 826 F.2d 420, 421 (5th Cir.1987)). The Shreves’ attempt to draw support from Freeman v. Case Corp., 118 F.3d 1011 (4th Cir.1997), cert. denied, 522 U.S. 1069, 118 S.Ct. 739, 139 L.Ed.2d 676 (1998), is unavailing. In Freeman> neither the qualifications of the proffered expert, nor the reliability of his methodology and opinions were contested. 118 F.3d at 1016 & n. 6. The issue presented was whether the expert testimony concerning design defect was sufficient to support the jury verdict. The Fourth Circuit explained: [The expert] did not simply opine on the basis of his “own subjective opinion.” Rather he applied his [several years of] experience and training in tractor design in reviewing numerous published materials, including papers by the Society of Agricultural Engineers, extensive industry literature, various tractor specifications, and trade journals before reaching his conclusions. [The expert] also inspected Freeman’s [tractor] and performed various tests on it, which indicated that the tractor did indeed lurch when both the SRC and brake pedals were pressed and the clutch released. Id. at 1016. In this way, the expert confirmed his hypothesis as to how the tractor accident could have occurred. Id. Dr. Shelley has no experience in the design of snow throwers for a manufacturer, and he has studiously refrained from testing his hypothesis concerning a possible defect in Shreve’s snow thrower. For the reasons stated, plaintiffs have not established by a preponderance of the evidence, see Cooper, 259 F.3d at 199, that Dr. Shelly’s ostensible use of fault tree analysis has permitted him to derive opinions as to causation that are reliably grounded in the field of engineering, and those opinions shall therefore be excluded. 2. Dr. Shelly’s Opinions As To The Discharge Chute Do Not Reliably Arise From A Valid “Risk Utility Analysis” Dr. Shelley purports to rely upon “risk utility analysis” to support his opinion that despite its compliance with all relevant industry standards, the snow thrower at issue had inadequate safeguards because an enclosed discharge chute and/or an “m wire” presented viable cost effective design alternatives that would have prevented Shreve’s accident. However, these opinions also founder on Dr. Shelley’s lack of qualifications and the failure to test his hypotheses. Dr. Shelley explained “risk utility analysis” as follows: The concept of risk-utility is, I hope, very well known. It simply means an evaluation of the benefit and utility of, as examples, a proposed guard or protective system, versus the decrease in utility of the product. A common, limiting example would be to fully enclose a circular saw blade: While the risk of injury would be completely eliminated, so would all the utility, since the saw could not cut any material. Hence, in actual designs the blade is only partially guarded. Shelley Aff. at 2-3. As explained above, apart from his work as an expert witness for product liability litigation, Dr. Shelley has no experience designing snow throwers, testing their safety, pricing or marketing them, or operating them. Dr. Shelley’s alleged “design” of an enclosed discharge chute can hardly be called a design. As depicted in his deposition exhibit 6, it is only the vaguest of sketches. He testified that the chute could possibly be eight or ten inches. It could be a relatively short distance. I’m not talking about three or four feet. It would look like a trombone horn. It would flare out so that you minimize the clogging problem, which I realize is a problem with snow throwers. But in the process of doing that, you start to really reduce the risk of injury. You’ll never eliminate it, because in order [sic] totally eliminate it, the machine wouldn’t do anything. You would have a totally useless snow thrower. Safe to use, but it doesn’t throw snow. So, as an engineer — and this is standard in all engineering analysis — you go through a risk utility study. And you decide, if you do this, what happens over here. But clearly, in something like this, it is my opinion that you could have somewhat of an enclosed discharge chute versus this thing, which is wide open .... First of all — and, again, this is done rather quickly — it would be basically some kind of any [sic] open flaring design. And clearly one can go through a very critical analysis as to what the radii of curvature would be of this thing and everything else .... And this would really prevent a person falling and getting his hand in the opening, compared to this thing which is wide open. This is like an open manhole in the street that you can fall right into. There’s absolutely nothing to stop you from moving into that opening. And, clearly there are a hundred flaring designs you could come up with. But this would be part of the design-engineer of the company through trying this, testing it, and easily making it. And it would add virtually nothing to the cost of the product. Shelley Dep. at 113-15 (emphasis added). Asked to clarify how far the chute would extend, Dr. Shelley replied: “It could be 8 to 15 inches. I mean, I really don’t know.” Id. at 116. Dr. Shelley admitted that he conducted no testing to ascertain whether the extended enclosed discharge chute would work or would increase the snow thrower’s safety. Indeed, he admitted that he had never used a snow thrower with such a device and that he was aware of no empirical data, studies or analysis of any kind to back up his claim that this design option would work. When pressed for verification of his claim he explained as follows: A: No. But what I will add to that is that I do know that it can be done. It’s a basic problem which would be modeled using fluid mechanics. Because snow stream can be modeled as a stream of moving particles. You can size the area, get the slope angles, do a very scientific analysis of that problem if you had to. Q: But my question to you, sir, is that aside from your believing it could be done- A: No, I’m not believing it. It’s a fact it can be done. Q: Aside from you saying it can be done, have you done it? A: No, I have not. Shelley Dep. at 118-19. Nevertheless, Dr. Shelley stated that the need for this guard was his “very considered professional opinion.” Id. at 112. After learning from the testimony of the defense experts, Sassaman and Elmy, that no manufacturer used a flaring enclosed discharge chute on a snow thrower, Dr. Shelley submitted a supplemental report after the deadline for expert submissions, offering the alternative of an “m wire” guard for the discharge chute. Shelley Dep. at 181. One manufacturer, Toro, uses an “m wire” guard on two or three of its snow thrower models. Dr. Shelley offered no testimony that he had ever used an “m wire” or tested it. He testified, nevertheless, that the flaring extended enclosed discharge chute would be the preferable alternative. Shelley Dep. at 189. Dr. Shelly’s alternative design testimony is inadmissible. With all respect, Dr. Shelly’s deposition testimony regarding alternative designs reads like the transcript of a brainstorming session attended by second semester undergraduate engineering students, not a serious effort to craft an admissible alternative design. I encouraged plaintiffs to arrange for Dr. Shelly to appear at the Daubert hearing in this case but he did not. I do not criticize plaintiffs in that regard, given the expense of such efforts, but as a consequence, I am left with the record described here. In my view, it is unmistakable that Dr. Shelly did not “employ[] in the [deposition] the same level of intellectual rigor that characterizes the practice of [mechanical engineering].” Cooper, 259 F.3d at 203. “Talking off the cuff — deploying neither data nor analysis — is not acceptable methodology.” Lang v. Kohl’s Food Stores, Inc., 217 F.3d 919, 924 (7th Cir.2000), cert. denied, 531 U.S. 1076, 121 S.Ct. 771, 148 L.Ed.2d 670 (2001). Moreover, “testing is important in alternative design cases.” Bourelle v. Crown Equipment Corp., 220 F.3d 532, 538 (7th Cir.2000). Considering the host of indicia to which courts have turned in evaluating the soundness of methodologies in alternative design cases, Dr. Shelly’s testimony falls far short of reflecting the level of reliability required and therefore will be excluded. See Milanowicz v. The Raymond Corp., 148 F.Supp.2d 525, 536 (D.N.J.2001)(“Thus, to recapitulate, among the in-dicia of reliability that courts may consider in evaluating expert testimony under Rule 702 are the following: 1) federal design and performance standards; 2) standards established by independent standards organizations; 3) relevant literature; 4) evidence of industry practice; 5) product design and accident history; 6) illustrative charts and diagrams; 7) data from scientific testing; 8) the feasibility of suggested modification; and 9) the risk-utility of suggested modification.”). 3. Dr. Shelly’s Opinions About Adequacy of Warnings Are Not Admissible Dr. Shelley’s report concludes that the “the lack of any safety warnings in the manual on the danger of losing one’s footing near the snow thrower, and making inadvertent contact with the exposed impeller blades, is a serious design defect of the Craftsman Snow Thrower.” Sept. 5, 2000 Report at 18. He proposed, off the top of his head during his deposition, that a proper warning would state: “Hazardous, sharp moving rotor in discharge opening. Use extreme caution when standing on slippery surfaces near discharge opening.” Shelley Dep. at 100. He acknowledged that he did not know whether any snow thrower manufacturer used comparable warning language, Shelley Dep. at 101, that such a warning is not specified by applicable ANSI standards, id. at 103, and that he was aware of no government agency or body that had raised any concern about the adequacy of the warnings for walk behind snow throwers. Id. at 105. The Owner’s Manual for the subject snow thrower warns in its initial safety rules: “Exercise caution to avoid slipping or falling, especially when operating in reverse.” Shreve Opp. Ex. E, Appendix A, p. B2 of 39. The safety rules also specify: “Do not put hands or feet near or under rotating parts. Keep clear of the discharge opening at all times.” Id. B3 of 39. They also state: “7. Stop the engine (motor) whenever you leave the operating position, before unclogging the auger/impeller housing, or discharge guide, and when making any repairs adjustments or inspections.” In addition, the rules admonish: “9. Take all possible precautions when leaving the snow thrower unattended. Disengage the auger/impeller, shift to neutral, stop engine, and remove key.” Id. The safety rules state in different places to “wear footwear that will improve footing on slippery surfaces,” id., and, “[ajlways be sure of your footing, and keep a firm hold on the handles. Walk; never run.” Id. at B4 of 39. Warning labels on the snow thrower itself show a foot near the auger with the words “¡Danger Avoid injury from rotating auger keep hands, feet and clothing away!” id. at B4 of 39, and a picture of a hand near the impeller blades in the discharge chute with the words: “! Danger stop the engine before unclogging discharge chute!” Id. For the reasons stated above, Dr. Shelley is no more qualified than any member of the jury to offer opinions about the adequacy of warnings for snow throwers. In addition, plaintiffs offer no empirical data or testing to support Dr. Shelley’s conclusions as to the desirability and adequacy of the warnings and instructions provided by defendants here. “The same reliability requirements that apply to alternative designs apply to alternative warnings.” Bourelle, 220 F.3d at 538 (citations omitted). Accordingly, Dr. Shelley is precluded from offering an expert opinion in this case. C. Defendants’ Experts Are Qualified and to the Extent Their Opinions May Be Relevant, They Are Admissible The Shreves responded to defendants’ motion to exclude Dr. Shelly’s testimony and filed their own “Motion to Conditionally Strike Defendants’ Experts” (“Shreve Cross Mot. to Preclude”). Stating “[wjhat’s good for the goose is good for the gander,” the Shreves’ cross-motion adopted “by reference” the defendants’ motion to exclude experts, as well as defendants’ memorandum of law. Shreve Cross Mot. to Preclude at 2-3. The Shreves argued that because the defense experts, Elmy and Sassaman, failed to test Shreve’s snow blower under conditions similar to those obtaining on the date of the accident, they failed to offer reliable opinions disproving Dr. Shelly’s ice buildup theory. Plaintiffs have misconstrued the defense burden with regard to plaintiffs’ theory of causation. First, the Shreves have misread the nature of the defense expert testimony. Sassaman and Elmy testified that had Shreve followed the operating manual safety rules and turned off the motor while leaving it unattended to retrieve his gloves, Shreve’s injury never would have occurred. Sassaman Report at 10. They each also testified that Dr. Shelley’s theory of ice build-up in the groove in the underside of the driven pulley has never been documented by anyone and is impossible. Elmy testified that he has participated in the testing of many snow throwers under numerous snowy conditions, though not the exact conditions present during Shreve’s accident. Sassaman is qualified to offer expert testimony concerning the design, safety, and operation of snow blowers. He has a B.S. in mechanical engineering and has worked professionally in the design, manufacturing, safety, and testing of outdoor power equipment for over 30 years. During these years, he has had extensive involvement in the design and testing of snow throwers, including four years as chief engineer for a manufacturer of snow throwers. He has participated in the development and application of snow thrower standards of the American National Standards Institute and the International Standards Organization. Sassaman also inspected Shreve’s snow thrower. Raymond Elmy is likewise qualified to offer expert testimony concerning the design, safety, and operation of snow throwers. He has a B.S. and a number of graduate courses in mechanical engineering and has worked for Murray for over 43 years. Since 1984 he has served as Vice-President of Design Engineering at Murray, and he holds various patents relating to the design of outdoor power equipment. During his employment with Murray, he has regularly engaged in the design, operation, testing, and evaluation of outdoor power equipment, including snow throwers. He has participated extensively with the American National Standards Institute and governmental groups, including the Consumer Product Safety Commission, in the promulgation of safety standards for, or oversight of the safety of, consumer outdoor power equipment, including snow throwers. He also inspected Shreve’s snow thrower. Elmy’s report states several conclusions, including: (1) “A power transmitting V-belt generates heat from cyclic bending and external friction .... [Additional heat energy is conducted to the belt from the engine;” (2) A diverging fully enclosed extension tube over the impeller would decrease the safety of the machine by increased discharge clogging; (3) No walk behind consumer snow thrower has a rigid flaring enclosed discharge chute; (4) Water cannot migrate to the pulley or its groove, and the pulley’s high rotational speed would impart centrifugal force on any substance located on its surface; (5) It is not possible to build up enough ice on the auger/impeller drive pulley groove such that the belt slack utilized for clutching purposes is completely taken up by the accumulated ice in the pulley groove; (6) The cause of the accident was Shreve’s failure to follow safety messages located on-product and in the manual that instructed the user to turn off the engine when the user left the operator’s position in addition to losing his footing when in close proximity to the machine while it was running. Elmy testified on deposition that while he had not tested snow throwers “under those very specific conditions” present during Shreve’s accident, “we have tested snow throwers extensively over the years under all kinds of snow conditions, and ice just doesn’t happen.” Elmy Dep. at 137. It is thus obvious that, unlike Dr. Shelley, both Sassaman and Elmy are qualified to offer expert testimony concerning the design, safety, and operation of snow throwers. Furthermore, neither Sassaman nor Elmy is a proponent of Dr. Shelley’s untested ice build-up theory and thus neither of defendants’ experts has the burden of demonstrating that this theory of causation is anything other than pure conjecture. Put simply, there is no burden on Sassaman or on Elmy to conduct tests in an effort to disprove an opinion held by Dr. Shelley. The burden is on the Shreves, as plaintiffs in this case, to justify the reliability of Dr. Shelley’s design defect conditions. Cooper, 259 F.3d at 199 (“The proponent of the testimony must establish its admissibility by a preponderance of proof.”) (citing Daubert, 509 U.S. at 592 n.