In this products liability claim under maritime law, a jury rendered a defense verdict. The principal issue on appeal is the proper application of Federal Rule of Evidence 702 to the proffered testimony of plaintiffs' experts.

Because this matter has been twice before our court, see Calhoun v. Yamaha Motor Corp., U.S.A., 40 F.3d 622 (3d Cir. 1994); Calhoun v. Yamaha Motor Corp., U.S.A., 216 F.3d 338 (3d Cir.2000), and also before the Supreme Court, see Yamaha Motor Corp., U.S.A. v. Calhoun, 516 U.S. 199, 116 S. Ct. 619, 133 L. Ed. 2d 578 (1996), its tragic facts have been well documented. But we detail certain facts as they relate to the matters currently under appeal.

In June 1989, twelve-year-old Natalie Calhoun was vacationing with her friend, thirteen-year-old Melanie Fox, and Melanie's family at the Palmas del Mar resort in Puerto Rico. On June 6, Melanie's mother, Corinne Fox, gave permission to the girls to rent a jet ski at the marina. Melanie and Natalie rented a Yamaha Wavejammer WJ500G Personal Water Craft from nineteen-year-old Samuel Roffe, a beach concessionaire at the Palmas del Mar resort. Affixed to the jet ski was a warning that the minimum recommended age for operation was fourteen. Neither girl had ridden a jet ski before.

In Natalie's presence, Roffe gave Melanie ten minutes of instruction. No parents or guardians were present at this time. While Melanie was riding the jet ski, her mother arrived at the marina. Roffe assured Mrs. Fox that riding the jet ski was "safe." After Melanie's uneventful thirty minute ride, she reported that the jet ski was "fun" and "easy."

When it was Natalie's turn, she was uncertain and expressed doubts. Mrs. Fox left the decision to Natalie, and eventually, she elected to ride. Roffe asked Natalie whether she was the requisite fourteen years of age, and she responded affirmatively. Roffe then gave her the same instructions given to Melanie. Natalie mounted the machine and began her ride in the lagoon near the resort.

Unlike Melanie, however, Natalie struggled and fell off while attempting to turn. Alarmed by this development, Mrs. Fox urged Roffe to "bring her back." Roffe rode out to Natalie in another jet ski, but by the time he reached her, she had remounted and assured him she was "okay." Natalie restarted the jet ski, made a sudden turn, and planed at high speed across the lagoon toward an anchored boat. As she approached the boat, she screamed but did not appear to attempt to veer away. Roffe testified she appeared "frozen" and "scared stiff." Tragically, Natalie crashed into the boat and died from massive head and neck trauma.

Natalie's parents, Lucien and Robin Calhoun, brought suit against Yamaha Motor Company, Ltd. and Yamaha Motor Corporation, U.S.A., the manufacturer and distributor of the jet ski.1 The Calhouns asserted several bases for recovery, including strict liability, negligence, and breach of implied warranties of merchantability and fitness for a particular purpose. Plaintiffs focused on an alleged defect with the design of the jet ski's accelerating mechanism, which is referred to as a "squeeze finger throttle" and resembles the braking mechanism on a bicycle. Plaintiffs also alleged the warnings were inadequate. The warning on the foot well of the jet ski provided in part:

A MINOR USING THIS WATER VEHICLE REQUIRES CLOSE ADULT SUPERVISION. CHECK FEDERAL/STATE LAWS FOR MINIMUM AGE REQUIREMENTS.

After several appeals, the suit went to trial.2 A jury rendered a verdict for defendants.

At trial, the District Court made several rulings that plaintiffs challenge on appeal. Although the District Court permitted plaintiffs' three expert witnesses to testify, it limited the extent of their testimony. Moreover, the District Court refused to submit the negligence claims to the jury, holding that plaintiffs could proceed only on their strict liability claims.3 Furthermore, in jury interrogatories4 and instructions,5 the District Court applied comparative fault principles and conditionally asked the jury to consider the negligence of two non-parties to the suit.

The jury returned a verdict in favor of Yamaha on the strict liability claims. The Calhouns appeal, arguing that errors made by the District Court require reversal and a new trial.6 Yamaha cross-appeals, contending the District Court should have precluded the testimony of plaintiffs' experts altogether and granted its motion for summary judgment.

Plaintiffs proffered three expert witnesses to testify at trial. After conducting extensive Daubert hearings including individual voir dire, the District Court determined that all could testify but limited the extent of their testimony. We review for abuse of discretion. See Gen. Elec. Co. v. Joiner, 522 U.S. 136, 138-39, 118 S. Ct. 512, 139 L. Ed. 2d 508 (1997) ("[A]buse of discretion is the appropriate standard" for "reviewing a trial court's decision to admit or exclude expert testimony.").7

Fed.R.Evid. 702 governs the admissibility of expert testimony. The Rule provides:

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.

Fed.R.Evid. 702. Amended in 2000, Fed. R.Evid. 702 represents the logical outgrowth and memorialization of the Supreme Court's landmark cases establishing the standards for admitting expert testimony.8 In Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S. Ct. 2786, 125 L. Ed. 2d 469 (1993), the Supreme Court charged trial judges with the responsibility of acting as "gatekeepers" to exclude unreliable expert testimony, id. at 597, 113 S. Ct. 2786, and in Kumho Tire Co. v. Carmichael, 526 U.S. 137, 119 S. Ct. 1167, 143 L. Ed. 2d 238 (1999), clarified that this "gatekeeper" function applies not only to testimony based on "scientific" knowledge but to testimony based on "technical" and "other specialized" knowledge as well. Id. at 141, 119 S. Ct. 1167.9

We have addressed the requirements of Fed.R.Evid. 702, focusing on the "trilogy of restrictions on expert testimony: qualification, reliability and fit." Schneider v. Fried, 320 F.3d 396, 405 (3d Cir.2003). First, the witness must be qualified to testify as an expert. Qualification requires "that the witness possess specialized expertise." Id. "We have interpreted this requirement liberally," holding that "a broad range of knowledge, skills, and training qualify an expert as such." In re Paoli R.R. Yard PCB Litig., 35 F.3d 717, 741 (3d Cir.1994) ("Paoli II"). Second, the testimony must be reliable. In other words, "the expert's opinion must be based on the `methods and procedures of science' rather than on `subjective belief or unsupported speculation'; the expert must have `good grounds' for his or her belief." Id. at 742 (quoting Daubert, 509 U.S. at 590, 113 S. Ct. 2786). An assessment of "the reliability of scientific evidence under Rule 702 requires a determination as to its scientific validity." Id. Third, the expert testimony must "fit," id. at 743, meaning "the expert's testimony must be relevant for the purposes of the case and must assist the trier of fact." Schneider, 320 F.3d at 405.

Here, the dispute centers on the second element, whether the proffered testimony of plaintiffs' experts was reliable. While defendants asserted the experts' qualifications were lacking in general, the thrust of their challenge was that the proposed testimony did not derive from scientific methods and procedures, but was simply unsupported opinion. In this respect, the District Court held that certain aspects of the experts' proposed testimony lacked proper foundation and was inadmissible.

In determining whether testimony is reliable, we are guided by several factors:

(1) whether a method consists of a testable hypothesis; (2) whether the method has been subject to peer review; (3) the known or potential rate of error; (4) the existence and maintenance of standards controlling the technique's operation; (5) whether the method is generally accepted; (6) the relationship of the technique to methods which have been established to be reliable; (7) the qualifications of the expert witness testifying based on the methodology; and (8) the non-judicial uses to which the method has been put.

Paoli II, 35 F.3d at 742 n. 8. In assessing reliability, a court need not rely exclusively on this list and may take into account any other relevant factors, id. at 742; however, this list provides an ample starting point.

With this framework in mind, we examine each expert's proposed testimony. The District Court carefully and thoughtfully restricted testimony that offered opinions on specific matters without reliable foundation. For example, the District Court declined to permit testimony on the proper age requirement for jet ski operators, without any specific support—such as studies or data indicating that persons above a certain age are more capable of operating the jet ski. While the background, education, and training may provide an expert with general knowledge to testify about general matters, more specific knowledge is required to support more specific opinions.

Plaintiffs proffered Dr. Edward W. Karnes to testify that the jet ski was defectively designed because riders would accidentally activate the throttle by clenching their hands as a "stress reaction." Plaintiffs also proffered Dr. Karnes to testify that the warnings on the jet ski should have restricted operation to those sixteen and older. The District Court prevented Dr. Karnes from testifying on these matters.

Dr. Karnes holds a doctorate in experimental psychology and is an emeritus professor of psychology at Metropolitan State College in Denver. Among his specialties is human factors engineering.10 He worked as a human factors engineer at the Martin Marietta Corporation in Denver, serving as the head of human factors research for six years. Although defendants stress that Dr. Karnes has no degree in engineering and lacks expertise in marine vessel design or operations, the District Court qualified him as an expert because of his extensive experience in general design and operations.

An expert may be generally qualified but may lack qualifications to testify outside his area of expertise. The District Court allowed Dr. Karnes to describe the squeeze finger throttle on the jet ski and to testify that because of the throttle's similarity to a bicycle brake, a child in a stress situation would naturally squeeze the mechanism in order to stop the jet ski. Dr. Karnes's other theory was not permitted—that as a "stress reaction," a person would have a tendency to clench her hands, which would inadvertently activate the squeeze finger throttle of a Yamaha jet ski. Furthermore, Dr. Karnes was not permitted to offer an overall conclusion that the design of the throttle was defective.

With respect to warnings, the District Court allowed Dr. Karnes to testify in general about how to design an effective warning. Dr. Karnes was also permitted to opine that the warning on the jet ski deviated from the proper criteria, making the "vehicle unreasonably dangerous and defective, especially for youthful operators." But the District Court prohibited Dr. Karnes from testifying that, in addition to its other alleged flaws, the warning on the jet ski should have restricted operators to those sixteen and older because Dr. Karnes did not have "anything to say to support that number rather than a number higher or lower."

The District Court gave Dr. Karnes some leeway in testifying about certain matters. Dr. Karnes's general knowledge of human factors engineering, along with his review of the record evidence, provided an adequate basis for his general description of the accelerating mechanism. But there was no support for Dr. Karnes's opinion on an asserted "tendency" to clench hands as a "stress reaction." There was no literature confirming this theory, nor demonstrable tests. Lacking support, his testimony was speculative and unreliable. With no reliable foundation, the District Court did not abuse its discretion by prohibiting any conclusory statements on the throttle's design.

Similarly, Dr. Karnes's general knowledge in the fields of psychology and human factors engineering may allow him to testify regarding proper warnings in general. But proffering admissible testimony that the proper age for jet ski use is sixteen or above requires more specific knowledge. The District Court did not abuse its discretion in prohibiting Dr. Karnes's proffered opinion that sixteen must be the minimum age.

Plaintiffs proffered Albert Bruton to testify that Yamaha's accelerating mechanism was not as safe as other alternative designs and that Yamaha's warning should have limited operation to those sixteen and older. The District Court refused to allow the proffered testimony.

Bruton, a lieutenant for San Diego's Marine Safety Services for sixteen years, had extensive experience with jet skis. He also had some experience designing warning signs for public use, such as signs designating certain marine areas for particular purposes, although he never designed a warning label for a jet ski or any other product sold to the public. Bruton had also conducted "aquatic related accident" investigations. As defendants note, Bruton lacks formal education or training in engineering, psychology, or human factors.

Bruton's testimony was also restricted. The District Court allowed Bruton to explain how jet skis operate and the differences between Yamaha's jet ski and other brands and models. Bruton was also permitted to discuss various accelerating mechanisms, explaining how each type works. A videotape was played showing Bruton riding a jet ski. But Bruton was prohibited from opining as to which jet skis, and particularly which accelerating mechanisms, were safer because the District Court found his "ranges of experiences" did not give him the expertise or knowledge to make this determination.

The District Court permitted Bruton to testify about how to frame an effective warning in general, for example, how words should be arranged and lettered. But the District Court prohibited him from opining on the proper substance of a particular warning, including proposed testimony that jet ski operations should be restricted to those sixteen and older.

These limitations were well considered. Because Bruton was knowledgeable about different types of jet skis and their operation, it was appropriate for him to explain such matters to the jury. But as noted, Bruton had no education or experience in product design of jet skis or accelerating mechanisms; nor did he provide scientific, statistical or other evidence evaluating the relative safety of different jet ski models or their accelerating mechanisms. Bruton had neither the general background nor the specific knowledge to support his proffered testimony that the "squeeze finger throttle" was less safe than other designs.

With respect to warnings, Bruton was given much leeway, especially considering he had never designed a warning for any consumer product. As for his proffered testimony on the specific substance of such warnings, particularly the age requirement, Bruton offered no support for his beliefs. His proffered opinions on these matters were unreliable, and the District Court properly restricted such testimony. There was no abuse of discretion.

Plaintiffs proffered Dr. Robert A. Warren to testify that the accelerating mechanism was unsafe because it resembled a bicycle brake and that Yamaha's warnings were inadequate. The District Court restricted Dr. Warren's testimony on these matters.

Dr. Warren has a bachelor's degree in naval architecture and marine engineering, as well as higher degrees in other fields. He worked with the Navy and the Department of Defense and served as an accident reconstruction consultant with a focus on marine engineering and boat accidents. Defendants acknowledge that Dr. Warren's qualifications are generally sufficient, and the District Court correctly held that his background qualified him to testify as an expert.

But as with the other experts, the District Court restricted the specifics of Dr. Warren's testimony. The District Court allowed Dr. Warren to describe the squeeze finger throttle on the jet ski but forbade his proffered testimony that the throttle was unsafe particularly due to its similarity to a bicycle's braking mechanism. The District Court also prohibited Dr. Warren from offering testimony about warnings.

Although Dr. Warren possessed expertise in relevant fields, he failed to apply this expertise to the matter at hand. At the time he wrote his expert report, Dr. Warren had never operated a jet ski and, by the time of trial, had only managed to ride a different model. Moreover, on voir dire, Dr. Warren admitted he had never examined diagrams of the different throttles used on jet skis. Dr. Warren's asserted knowledge of possible alternatives to the accelerating mechanism came from his familiarity with outboard motors, which employ a twist grip mechanism, and from his recollection of a friend's motorcycle, which used a thumb throttle. Dr. Warren acknowledged he could have conducted tests to evaluate the relative merits of alternative throttle designs but did not do so. With such a paucity of knowledge regarding the specifics of jet ski accelerating mechanisms, Dr. Warren was unable to give reliable testimony on whether Yamaha improperly employed the squeeze finger throttle on its jet ski. Although Dr. Warren had sufficient knowledge to describe the throttle mechanism in general, the District Court properly precluded him from giving further opinions on the matter.

Similarly, Dr. Warren lacked any specific basis on which to opine on the adequacy of Yamaha's warnings. Moreover, in contrast to his background in naval architecture and marine engineering, which provided Dr. Warren the foundation to testify generally about mechanical issues, he possessed no expertise with regard to warning design. Thus, the restriction on testimony regarding warnings was proper. There was no abuse of discretion.

Plaintiffs contend that the District Court erred at the close of evidence in granting defendants' motion for judgment as a matter of law on their negligence claims. See Fed.R.Civ.P. 50. We exercise plenary review. See, e.g., Shade v. Great Lakes Dredge & Dock Co., 154 F.3d 143, 149 (3d Cir.1998) ("This court utilizes a plenary standard to review a grant ... of a judgment as a matter of law.").

Negligence claims are cognizable in admiralty and may be asserted in addition to strict liability claims. E. River S.S. Corp. v. Transamerica Delaval, Inc., 476 U.S. 858, 865-66, 106 S. Ct. 2295, 90 L. Ed. 2d 865 (1986). But the question here is whether plaintiffs' evidence supported these claims. The District Court explained that, while the negligence claims were "there in the complaint," they "ha[d] not... survived in any real sense" during the course of the trial. As such, the District Court held that the negligence claims "ha[d] not been made out" and could not be submitted to the jury.

We agree. It is clear that the focus of the trial evidence was on plaintiffs' strict liability claims. Plaintiffs provided only cursory theories of Yamaha's alleged negligence and offered scant support to sustain them. The negligence claims should not have been submitted to the jury. Judgment as a matter of law was proper.

Plaintiffs argue the District Court erred in submitting to the jury the possible comparative negligence of Roffe and/or Palmas del Mar, neither of which were party to this suit. According to plaintiffs, rules of joint and several liability should govern, and the possible negligence of nonparties cannot be considered. As plaintiffs allege an error of law, our review is plenary. See, e.g., Harris v. City of Philadelphia, 47 F.3d 1342, 1349 (3d Cir.1995).

Though we think it likely there was no error, given our other rulings, any error would be harmless. It was harmless because the court's instruction could not have affected the jury's verdict on the strict liability claim, in that the jury decided as a threshold matter, that the jet ski was not defective. In instructing the jury, the District Court stated:

Now, members of the jury, if and only if you decide that the Wavejammer was defective in a way that proximately caused Natalie's death, you must then consider whether [Roffe and/or Palmas del Mar] committed negligent acts that contributed to the accident.

Furthermore, the interrogatories clearly provided that the first issue to be considered was whether Yamaha's jet ski was defective. The possible negligence of Roffe and/or Palmas del Mar mattered only if Yamaha were liable. Because the jury found that the jet ski was not defective, it never reached the possible negligence of Roffe and/or Palmas del Mar.

In this respect, the matter here is similar to that addressed in Dillinger v. Caterpillar, Inc., 959 F.2d 430 (3d Cir.1992). In Dillinger, plaintiff sued under strict liability for injuries he sustained while driving a vehicle manufactured by defendant. Id. at 432. The district court allowed defendant to introduce evidence that plaintiff was not wearing a seat belt but only for considering mitigation of damages. Id. We held that it was error for the district court to allow such evidence because "the introduction of ... non-use of the seat belts would be directly at odds with the [state] Supreme Court's dictates barring evidence of a plaintiff's negligence in [strict] liability proceedings." Id. at 439. But we concluded that such error was harmless because the jury had determined that the defendant's product "was either not defective or that the defect was not a substantial factor in causing the accident," and thus the jury never reached the issue of seat belt use. Id. at 440. While plaintiff argued "that the jury was influenced by the evidence concerning [his] failure to use the available lap belt in determining whether [defendant's] product was defective or whether a defect caused [plaintiff's] injuries," the court had to "assume that the jury was competent to follow and did follow the instructions given." Id. at 440 n. 17.11

For these reasons, we will affirm the judgment of the District Court.