Iowa Code § 321I.19: Negligence.

The owner and operator of an all-terrain vehicle are liable for any injury or damage occasioned by the negligent operation of the all-terrain vehicle. The owner of an all-terrain vehicle shall be liable for any such injury or damage only if the owner was the operator of the all-terrain vehicle at the time the injury or damage occurred or if the operator had the owner’s consent to operate the all-terrain vehicle at the time the injury or damage occurred.