In a unanimous decision, the Arizona Supreme Court clarified decades of imprecise product liability decisions and did so in the context of cutting-edge technology. Affirming that Arizona requires proof of both defect and unreasonable dangerousness—and that these are analytically distinct elements—it affirmed summary judgment for Toyota, concluding that the absence of an advanced driver assistance system (ADAS) did not render a vehicle defective.
Maywald v. Toyota, No. CV-25-0009-PR (July 7, 2026), arose out of a crash in which the driver of a 2019 Toyota 4Runner fell asleep at the wheel, crossed a highway dividing line and caused a head on collision with a full-sized van. The van’s occupants sued Toyota, alleging that Toyota was liable because if the 4Runner had been equipped with lane departure warning (LDW)—an ADAS feature that could, under some circumstances, alert a driver that he had left the intended lane of travel—this crash supposedly would not have occurred. Toyota moved for summary judgment on several grounds, including that there was no defect as nothing about the 4Runner was defective or caused this crash or the plaintiffs’ injuries. The superior court agreed, pointing out that under Arizona law, a driver, not a car, is responsible for maintaining a vehicle in the correct lane of travel.
The plaintiffs appealed and the Arizona Court of Appeals reversed in an unpublished memorandum decision. That court concluded that a plaintiff need not separately prove that a product is defective and could use the risk-benefit or consumer expectations test to establish that a product is defective and unreasonably dangerous. It then agreed with plaintiffs that a jury could find in their favor if it concluded that the benefits of the ADAS system outweighed the risks of the vehicle without it.
Toyota petitioned for review to the Arizona Supreme Court. The Court accepted review, vacated the court of appeals and affirmed the trial court’s grant of summary judgment. It explained that although precedent established nearly fifty years ago was clear that defect and unreasonable dangerousness are two elements, in the interim, courts had tended to improperly collapse and conflate them. It re-affirmed that a plaintiff has a burden of showing a defect—that a product is unsafe for normal handling and consumption. Only after making that showing can the plaintiff move on to one of the tests for unreasonable dangerousness (the consumer expectation or risk-benefit tests).
The Court then found as a matter of law that the 4Runner was not defective without LDW. It explained, “consumers reasonably expect that vehicles are designed to allow them to drive within marked lanes and we agree with Toyota that the Maywalds failed to establish that the 4Runner did not deliver on that expectation.” (Opinion ¶ 26.) And “[a]lthough LDW technology may enhance vehicle safety, it does not eliminate the driver’s fundamental responsibility to maintain control of the vehicle.” (Id.). In reaching this conclusion, the Court cited with approval Berkoski v. American Honda Motor Co., Inc., 328 A.3d 986 (N.J. Super. App. 2025), which similarly concluded that vehicles are not defective merely because an additional safety feature was available.
Although the Court’s finding of no defect was dispositive, it also clarified the operation of the risk-benefit test because the Court of Appeals had misapplied it. The Court confirmed that the “inquiry focuses on the risks and benefits inherent in the challenged design itself” and not from “weighing the risks and benefits of an alternative design” as the court of appeals had done. (Opinion ¶ 33.) The Court explained, “[w]ere it otherwise, manufacturers would essentially be required to incorporate every feasible safety feature or face potential liability.” (Id.)
This opinion provides both necessary clarity on points of Arizona law that have been misconstrued as well as important precedent for manufacturers who have been sued in cases where the plaintiff alleges that the failure to equip their products with the ultimate safety features amounts to a defect.
Toyota was represented in this matter by Jim Halbrooks, Will Auther, Wendy Lumish, Alex Egbert and Amanda Heitz of Bowman and Brooke LLP.