Background
The Utah Court of Appeals affirmed Asael Lyman’s conviction for negligently operating a vehicle resulting in death after rejecting his theory that an unforeseeable cardiac event caused the fatal collision. The evidence permitted the jury to find negligent operation, and the trial court was not required to give Lyman’s proposed medical-event instruction. A possible error in instructing on prima facie evidence of speeding was harmless beyond a reasonable doubt.
Lyman drank whiskey during the night and later drove to pick up his grandson. His truck entered a Bangerter Highway off-ramp at extreme speed, struck a concrete barrier, crossed a divider and red light, and hit another truck, killing its driver. Event data showed speeds up to ninety-seven miles per hour and full accelerator input. A blood draw showed an alcohol concentration of 0.12.
The defense argued that atrial fibrillation caused Lyman to lose consciousness unexpectedly. Experts disagreed about whether his persistent atrial fibrillation likely produced fainting and whether steering data reflected conscious correction. Lyman testified that he remembered approaching the off-ramp and next remembered a paramedic. The jury convicted him of negligent operation resulting in death and other offenses.
The Court’s Holding
Judge Christiansen Forster’s opinion held that the trial judge properly denied a directed verdict and a motion to arrest judgment. Viewed in the light favoring the verdict, the alcohol evidence, speed, accelerator position, path of travel, expert opinions, and apparent steering correction allowed a reasonable jury to reject the loss-of-consciousness account and find negligent operation caused the death.
The court also upheld refusal of a proposed instruction on an unforeseeable medical condition. The requested language was not necessary to let the defense argue its theory under the instructions as a whole, and the trial court stayed within its discretion. Although an instruction concerning prima facie evidence of speeding may have been erroneous, other evidence of negligence and causation was overwhelming enough to render any mistake harmless beyond a reasonable doubt.
Finally, excluding testimony from Lyman’s son about hundreds of earlier uneventful trips was not an abuse of discretion. Familiarity with the intersection did not make intoxicated driving or sudden unconsciousness more likely, and Lyman had already testified that he frequently made the trip and knew the route. The proposed evidence was therefore irrelevant or cumulative. With only a possible harmless instruction error, cumulative error did not apply.
Key Takeaways
- A sudden-medical-event defense remains a factual question when competing expert and vehicle-data evidence supports consciousness and negligent driving.
- Courts assess jury instructions as a whole and need not adopt a party’s preferred wording when the theory can otherwise be argued.
- Evidence of prior uneventful trips may be irrelevant and cumulative when route familiarity does not resolve the cause of the charged collision.
Why It Matters
For Utah DUI and vehicular-homicide litigation, Lyman demonstrates the importance of integrating medical testimony with objective vehicle data. A defense expert should address accelerator force, steering input, braking, timing, and the type of cardiac condition rather than offer a medical possibility in isolation. Prosecutors likewise should connect each data point to consciousness, negligence, and causation.
The harmless-error analysis also counsels precise objections to statutory or prima facie-evidence instructions. Counsel should explain how the instruction changes the jury’s treatment of a disputed element and why the remaining proof does not independently establish guilt. Evidence of a driver’s normal habits or prior safe trips needs a clear relevance theory beyond general familiarity with the roadway.