The unanimous opinion by Justice Nielsen revives a wrongful-death suit brought by Yesneiri Maldonado-Velasquez, whose husband Emilio Martinez-Arroyo was killed when the Volkswagen Jetta in which he was a passenger struck the rear of a Peterson trailer on I-80 in Parley's Canyon and slid underneath it. The driver, Raul Lopez, was also killed. The trailer carried no underride protection.

The Third District Court had granted partial summary judgment to Peterson, reasoning that Utah Code § 41-6a-206 — which provides that federal motor carrier rules "supercede any conflicting provisions" of the state traffic code — foreclosed any duty to upgrade a trailer that met federal standards. Applying the multi-factor test from B.R. ex rel. Jeffs v. West, the trial court declined to recognize a duty to "augment or modify" the trailer.

Justice Nielsen wrote that the lower court "used Jeffs to negate an applicable statutory duty." The court reiterated that the Jeffs factors apply only "when a party seeks to establish a previously unrecognized duty for a category of cases" and "do[] not apply when a plaintiff invokes a categorical duty already recognized under Utah law."

The applicable duty, the court said, comes from Utah Code § 41-6a-1601(1)(a)(i), which bars operating a vehicle "in an unsafe condition that may endanger any person." That statute, Justice Nielsen wrote, "protects any person traveling on a highway from the exact type of harm that allegedly occurred in this case."

Turning to preemption, the court held that the Federal Motor Carrier Safety Regulations operate under a conflict-preemption scheme. "[F]ederal law is a floor, not a ceiling, in this area, and state law falls only if it is impossible to comply with both," the opinion states. "State law can impose a level of duty exceeding federal motor carrier regulations because it is possible to adhere to such a standard without making it impossible to comply with that federal floor."

The court also addressed Peterson's argument that the negligence theory was a repackaged products-liability claim that could not be brought against a non-manufacturer. Justice Nielsen acknowledged that the enhanced-injury doctrine originated in products cases such as Larsen v. General Motors Corp., but, quoting a law-review article it adopted, wrote that "[t]he concept of recovery for enhanced injury . . . is far broader" and that an enhanced-injury claim "can go forward" against an operator who "improperly used an allegedly defective trailer."

The justices rejected Peterson's harmless-error argument, which rested on the jury's no-fault verdict. "The jury came to its no-fault verdict without what we have now held was relevant evidence about RJP's use and operation of the trailer," the opinion states. The court declined to affirm "even partially" on that basis and remanded for further proceedings.

The trial court had excluded much of the testimony of plaintiff's expert Byron Bloch on underride dangers and on whether the trailer's design caused Martinez-Arroyo's death. Because those rulings were "premised on the legally incorrect lack-of-duty ruling," the Supreme Court held, exclusion of the testimony as irrelevant was an abuse of discretion.

Chief Justice Durrant, Associate Chief Justice Pohlman, and Justices Petersen and Hagen joined the opinion. The court sat as a five-justice division under Utah Supreme Court Standing Order No. 18.

Maldonado-Velasquez was represented by Rodger M. Burge, Dick J. Baldwin, Steven R. Glauser and Daniel S. Sorenson of Salt Lake City, with Joseph Jardine of Farmington. Vincent J. Velardo and Thomas J. Rollins of Salt Lake City represented Peterson.