Baseball umpire Edwin Hickox was injured while wearing a mask manufactured by Wilson Sporting Goods Company. Mr. Hickox and his wife brought products-liability claims against Wilson. A jury found for the Hickoxes on all claims. Wilson appeals, arguing that the Hickoxes presented expert testimony that lacked an adequate foundation; that Wilson was entitled to a jury instruction on assumption of risk; and that the evidence was insufficient to support the verdict. We affirm.
I.
The Hickoxes’ evidence at trial indicated the following. In 2005, at an annual retreat for Major League Baseball umpires, a Wilson representative gave Mr. Hickox an umpire’s mask with what the representative claimed was a new, safer design. Several months later, Mr. Hickox wore the mask while working behind home plate as an umpire during a game in Washington, D.C. In the top of the ninth inning, a foul-tipped ball struck the mask. The impact of the ball gave Mr. Hickox a concussion and damaged a joint between the bones in Mr. Hickox’s inner ear. As a result, Mr.
The mask was a traditional umpire’s mask, but had a newly designed throat guard that angled forward instead of extending straight down. According to the Hickoxes, the throat guard should have had a center wire and should have extended straight down with no forward angle. Because the mask lacked these features, when the ball hit the throat guard, the mask did not deflect the ball but rather temporarily trapped the ball, concentrating the ball’s energy at the point of impact. As a result, the mask was driven into Mr. Hickox’s jaw with great force.
Safer, alternative masks were sold at the time of the incident. If Mr. Hickox had been wearing either a hockey-style mask or a traditional mask with a throat guard that extended straight down, he probably would not have suffered the injury.
Mr. Hickox believed that Wilson tested new products and ensured that they were safe before selling them. In fact, Wilson did not test the type of mask worn by Mr. Hickox to determine the forces that would be transferred to the wearer’s head upon impact. Such testing would have shown the mask to be defective, because the mask can trap balls rather than deflect them.
Mr. Hickox anticipated that the mask would disperse the force created when a ball hit the mask. That is what the product-design engineers at Wilson intended the mask to do and what Wilson’s representative told Mr. Hickox the mask would do. When Mr. Hickox was injured, the mask failed to serve this purpose, because of the mask’s defective design.
In contrast to the Hickoxes’ version of events, Wilson contended the following at trial. The ball hit the mask above the throat guard, not on it, and so the same injury would have occurred even if the mask had not had a throat guard at all. Wilson intended the mask to provide protection by deflecting balls away from the wearer’s head, and the mask accomplished this objective during the incident. At the time of the incident, there were no design or testing standards for wire baseball masks. The mask was designed using feedback from baseball players and umpires, and the forward angle improved the mask’s utility by preventing the throat guard from hitting against the umpire’s chest protector and dislodging or being knocked out of alignment.
Other companies sold masks with forward-angled throat guards, and those masks were not associated with injuries like Mr. Hickox’s. The mask had been field-tested for over five years, and had been lab-tested before the incident. Before the incident, Mr. Hickox had used the mask many times without injury. After the incident, Mr. Hickox suffered additional head injuries while umpiring, even though he was then wearing the hockey-style mask that he claimed to be a safer, alternative design.
Mr. Hickox was an experienced umpire who knew that participating in sports creates the risk of injury, that no face mask can guarantee safety, and that injury is more likely without protective equipment.
At the close of trial, the judge submitted several tort claims to the jury: strict liabil
II.
A.
Wilson asserts that the testimony of the Hickoxes’ expert witness, Dr. Igor Paul, was not based on adequate data and lacked a scientific foundation. See generally Sponaugle v. Pre-Term, Inc.,
At trial, Dr. Paul based his testimony on the following sources of information: freeze-frame and slow-motion analysis of the videotape of the incident; calculation of the energy possessed by a baseball when pitched at various speeds; published results of impact testing conducted on hockey-style helmets by an association that sets standards for sports helmets; and examination of the Wilson mask and other baseball masks.
Appellate courts have consistently upheld the admission by trial courts of comparable expert testimony. See, e.g., Orth v. Emerson Elec. Co., White-Rodgers Div.,
Wilson asserts that Dr. Paul’s testimony was deficient in several respects, but we conclude that the asserted deficiencies go to weight rather than admissibility. See generally, e.g., Benn v. United States,
1.
Wilson faults Dr. Paul for failing to conduct his own tests, but there is no requirement that an expert perform tests, particularly where the expert relies on published data generated by another expert in the pertinent field. See Gussack Realty Co. v. Xerox Corp.,
Wilson relies on several cases in which an appellate court affirmed a trial court’s exclusion of expert testimony in part because the expert had not done testing, but those cases are readily distinguishable. As a threshold matter, there is a critical difference between holding that a trial court did not abuse its discretion by excluding expert testimony, which is what was held in the cases cited by Wilson, and holding that a trial court abused its discretion by admitting expert testimony, which is what Wilson would have this court hold. Cf. McDaniel v. United States,
2.
Wilson also faults Dr. Paul for failing to provide an adequate explanation of his reasoning. Wilson is correct that courts should exclude expert testimony that consists of mere assertions. See, e.g., Viterbo v. Dow Chem. Co.,
It is true, as Wilson emphasizes, that Dr. Paul did not fully explain every aspect of his reasoning. In expert testimony, however, as “[i]n administrative proceedings ... [and] ordinary life, ‘explanations come to an end somewhere.’ ” Liskowitz v. Astrue,
3.
We are unconvinced by Wilson’s other challenges to the admissibility of Dr. Paul’s testimony. Wilson relies on several cases discussing the admissibility of expert testimony where the expert employs a particular theory or technique that is not accepted in the scientific community. Because Wilson does not allege that Dr. Paul’s testimony had this flaw, those cases are inapposite. Similarly unhelpful to Wilson are this court’s cases holding that an expert testifying to the standard of care in a negligence case could not testify solely to a personal opinion about what should have been done, but rather also had to demonstrate knowledge of the applicable national standard of care and testify as to whether that standard was met. Some of Dr. Paul’s testimony related to standard of care, and it may well be true that Dr. Paul’s testimony was not sufficient to establish a national standard of care. Wilson, however, was found liable on strict-liability theories that do not require proof of a national standard of care, and Dr.
Wilson does cite one products-liability case holding that a trial court abused its discretion by admitting expert testimony, but in that case the complete lack of evidence about consumer expectations rendered the expert’s testimony insufficient to establish a design defect. See Sexton v. Bell Helmets, Inc.,
In sum, the trial court did not abuse its discretion by admitting Dr. Paul’s testimony.
B.
Wilson asserts that it was entitled to have the jury instructed on an assumption-of-risk defense. We view the record in the light most favorable to Wilson and inquire whether an assumption-of-risk defense had sufficient evidentiary support. Haidak v. Corso, 841 A.2d 316, 320 (D.C. 2004). We find no error in the trial court’s determination that such support was lacking.
An assumption-of-risk instruction is warranted in a design-defect case if the defendant offers evidence that the plaintiff knew about the specific alleged defect and the associated danger. See Warner Fruehauf Trailer Co. v. Boston,
C.
Wilson argues that there was insufficient evidence to support judgment against it on any of the products-liability claims. We view the evidence in the light most favorable to the Hickoxes and will reverse only if no reasonable person could have rendered a verdict in the Hickoxes’ favor. Oxendine v. Merrell Dow Pharm., Inc.,
There are two tests commonly used to determine whether a product’s design was defective: the consumer-expectation test and the risk-utility test. Warner Fruehauf,
Wilson explicitly assented at trial to jury instructions that required the jury to make findings under a consumer-expectation test. Specifically, the jury was told that “[a] design is defective if the product fails to perform as safely as an ordinary customer would expect when [the product is] used in an intended or reasonably foreseeable manner.” This formulation is essentially equivalent to the consumer-expectation test as defined by this court and others. See Warner Fruehauf,
In the absence of manifest injustice, where an appealing party requested or acquiesced in a jury instruction specifying the elements of a cause of action, we have assessed the sufficiency of the evidence in light of the elements that were instructed to the jury, rather than in light of elements asserted by the appealing party for the first time on appeal. See District of Columbia v. Banks,
Viewed in the light most favorable to the Hickoxes, the evidence indicated that the mask at issue was more dangerous than comparable masks sold at the time, such as hockey-style masks, because the mask could concentrate energy at the point of impact, rather than distribute energy evenly throughout the padded area of the mask. Because the energy possessed by a pitched baseball is adequate to cause severe injury, the jury could reasonably have concluded that a mask that concentrated
The jury could also have relied on the existence of safer, commercially available alternatives to draw inferences about the level of safety an ordinary user would expect. See Whitted v. General Motors Corp.,
In addition, the jury could have concluded that the statements made by Wilson’s representative to Mr. Hickox about the mask reflected Wilson’s standard marketing approach, and that an ordinary consumer therefore would have expected the mask to perform more safely than other models. See Mikolajczyk v. Ford Motor Co.,
Evidence of industry practice can also be relevant to reasonable consumer expectations. See Alevromagiros v. Hechinger Co.,
Finally, liability for design defect requires proof that the defect proximately caused the plaintiffs injury. Warner Fruehauf,
The judgment of the trial court is therefore
Affirmed.
Notes
. After oral argument before this court, Wilson filed a motion to supplement the record with materials relating to a suit the Hickoxes filed in connection with the subsequent incident in which Mr. Hickox was injured. We deny Wilson’s motion. The information Wilson asks us to consider was not considered by the trial judge or jury. Barring unusual circumstances not present here, this court does not consider new materials on appeal. See Moorehead v. District of Columbia, 747 A.2d 138, 145 n. 12 (D.C.2000).
. Wilson suggests that it was not possible for Dr. Paul to see where the ball hit the mask in the video. Wilson does not appear to have objected to the video analysis on that basis at trial. Moreover, Wilson’s expert used the video in a similar manner at trial, testifying that in his opinion the video showed that the ball did not hit Mr. Hickox's throat guard. It is unclear whether Wilson now intends to suggest that Dr. Paul’s testimony about the video should have been excluded, but in any event we would not be persuaded by such an argument. Even if Wilson had objected at trial, it would not have been an abuse of discretion for the trial court to permit each witness to testify to his conclusions about what the video depicted, leaving it to the jury to assess that' conflicting testimony. Cf., e.g., Crymes v. State,
. Although federal law governing the admission of expert testimony differs from the law in this jurisdiction in some respects, we view federal cases as persuasive authority in the current context. See, e.g., Jones,
. Wilson asserts in passing that Dr. Paul’s testimony was inadmissible because Dr. Paul was not offered and qualified as an expert in testing. Wilson fails to brief that issue, however, and the issue therefore is not properly before this court. See Bardoff v. United States,
. The trial court and the parties derived this jury instruction from Standardized Civil Jury Instructions for the District of Columbia, No. 23.09, at 23-9 (2012 rev. ed.). The comment to that instruction indicates that either the consumer-expectation test or the risk-utility test may apply in this jurisdiction, “depending on the factual situation.” Id. at 23-10 (citing Warner Fruehauf,
. States that apply the consumer-expectation test do so in varying ways and circumstances, and some courts apply variants that include elements of both a consumer-expectation test and a risk-utility test. See generally Restatement (Third) of Torts: Prods. Liab. § 2, at 65-77, Part II(B)-(D) of Reporters’ Note to cmt. d (1998). We find the out-of-jurisdiction cases cited in this opinion instructive for current purposes, despite the differences in approach among the various jurisdictions.
. Wilson emphasizes that Mr. Hickox suffered injury in a second incident while wearing the same type of mask that the Hickoxes claimed to be a safer, alternative design. A single instance of failure, however, does not mean that the design of the second mask was not a safer alternative. To establish that the mask Mr. Hickox wore during the second incident was not a safer, alternative design, Wilson would have needed to present additional evidence, such as evidence that the first mask would not have failed in the second incident; that the second mask failed due to an aspect of its design rather than a manufacturing defect; or that there is a design trade-off such that avoiding the asserted design flaw of the first mask would require introducing the feature that caused the second mask to fail. Cf., e.g., Back v. Wickes Corp.,