OPINION

Per Curiam:

This appeal arises out of a traffic accident which occurred on July 25, 1978, when the automobile which was owned and operated by appellant George Barnes collided with a semi-truck owned by respondent Delta Lines, Inc. Shortly before the collision occurred, the driver of the truck, respondent Adolph Salazar, had apparently pulled the truck forward from the righthand side of the road, and was in the process of backing the truck into a private parking lot on that same side of the road. When Barnes collided with the truck, it was apparently blocking both of the eastbound lanes of the road in the direction in which Barnes had been traveling. Barnes suffered various injuries in this accident, and he and his wife, appellant Lisa Barnes, subsequently brought a cause of action alleging that respondents had negligently owned and operated a motor vehicle.

At the trial on this matter, the judge instructed the jury that it was a violation of Nevada law to fail to yield the right of way to moving traffic while backing a vehicle on a roadway, or when entering a highway from a private way. See NRS 484.321, 484.449. Appellants then requested that the judge give the following negligence per se instruction to be read in conjunction with the above instructions on Nevada traffic laws:

If you find that a party to this action violated any of the statutes just read to you and that such violation was a proximate cause of injury to another or to himself, you will find that such violation was negligence unless such party proves by a preponderance of the evidence that he did what might reasonably be expected of a person of ordinary prudence, acting under similar circumstances, who desired to comply with the law.

The trial judge refused to give this instruction, and the jury returned a verdict for respondents. Appellants now contend that the judge's refusal was error. We agree.

When a defendant violates a statute which was designed to protect a class of persons to which the plaintiff belongs, and thereby proximately causes injury to the plaintiff, such a violation constitutes negligence per se, unless the defendant can show that the violation was excused. See Gordon v. Hurtado, 96 Nev. 375, 609 P.2d 327 (1980); Southern Pacific Co. v. Watkins, 83 Nev. 471, 435 P.2d 498 (1967). See generally W. Prosser, Handbook of the Law of Torts, § 36 (4th ed. 1971). In the present case, the two traffic statutes in question were clearly enacted to protect motorists such as appellant Barnes from other motorists who negligently proceed onto a roadway without yielding the right of way to moving traffic. Moreover, since the questions of whether a violation of a statute occurred and whether the violation was a proximate cause of the plaintiff's injuries are questions of fact for the jury, see White v. Demetelin, 84 Nev. 430, 442 P.2d 914 (1968), we must conclude that it was error for the trial judge to refuse to give appellants' proposed instruction.

Additionally, we reject respondents' contention that the refusal to give the negligence per se instruction was not prejudicial to appellants' case. A negligence per se instruction would have served to shift the burden of proof to respondents to show excuse or justification, thereby relieving appellants of the burden of establishing actual negligence. See Lopez v. Bowen, 495 P.2d 64, 66 (Alaska 1972). As such, there is no question that the jury may have reached a different result in this case if it had been properly instructed on the law of negligence per se.

Accordingly, the judgment is reversed and the case is remanded for a new trial.