D lost control of his pickup truck as it slid across the centerline of the highway and collided with a northbound vehicle that was occupied by Ps. Ps brought this negligence action against D, seeking recovery for personal injuries and for the damage to their automobile. D had a two-wheel-drive pickup with new tires. It was in excellent condition and had its bed weighted down. The roads had been fairly clear but snow had fallen and made the road slippery. D proceeded at a constant speed of between forty and fifty miles per hour. Without warning, the back-end of his pickup slid left, toward the centerline. D tried to steer into the slide but the pickup slid at an angle, crossed the centerline, and collided with the Ps' vehicle. There was no evidence of negligence on the part of anyone in Ps' vehicle. Ps claimed D violated the law with respect to driving on the proper side of the road. The court instructed the jury as follows: A violation of a statute is negligence unless compliance with the statute was impossible or something over which the party had no control placed him in a position of violation of a statute or an emergency not of the party's own making caused him to fail to obey a statute. The jury returned a verdict for D. Ps moved for a judgment n.o.v., asserting that the undisputed evidence established D's violation, and that there was not sufficient evidence to support a finding that the violation was excused. Ps moved for a new trial. The motions were denied and Ps appealed.