Defendant assigns as error the failure of the trial court to charge the jury that if the officer were attempting to make an illegal arrest of C. T. Small on the charge of driving a motor vehicle on a public highway while under the influence of intoxicating liquor, the officer was not discharging a duty of his office and defendant would not be guilty of the crime charged.
*669One of the elements of the assault charge against the defendant was that Trooper Alley “was discharging a duty of his office, to-wit: attempting to arrest Talmadge Small, in violation of the following law: G.S. 14-33 (b) (4).” The burden was on the State to prove this element of the offense.
The offense of assaulting a law-enforcement officer while the officer is discharging or attempting to discharge a duty of his office presupposes lawful conduct of the officer in discharging or attempting to discharge a duty of his office. State v. Sparrow, 276 N.C. 499, 173 S.E. 2d 897 (1970); State v. Jefferies, 17 N.C. App. 195, 193 S.E. 2d 388 (1972), cert. denied, 282 N.C. 673, 194 S.E. 2d 153 (1973).
Trooper Alley was arresting or attempting to arrest Mr. Small on the charge of “driving under the influence,” a misdemeanor. G.S. 20-138(a). He did not have a warrant. He had the right to make a warrantless arrest of Small if he had probable cause to believe that, in his presence, Small was driving a motor vehicle on a public highway while under the influence of intoxicating liquor. G.S. 15A-401(b) (1). If he did not have probable cause to make the arrest, then the arrest or attempted arrest was illegal, and Trooper Alley was not discharging or attempting to discharge a duty of his office.
The reasonableness of the officer’s grounds to believe the defendant had committed a misdemeanor in the officer’s presence, when properly raised, is a factual question to be decided by the jury. State v. Jefferies, supra. Was the question properly raised in the case before us? Trooper Alley testified that he told Small that he was under arrest for “driving under the influence.” There was no conflicting evidence as to the two elements of this offense, to-wit: (1) on a public highway, and (2) while under the influence of intoxicating liquor. There was conflicting evidence as to the third element of the offense, driving a motor vehicle. It has been held that “driving” requires that the vehicle be in motion. State v. Carter, 15 N.C. App. 391, 190 S.E. 2d 241 (1972).
All of the evidence tends to show that Mrs. Small and Mrs. Simmons complied with Trooper Alley’s order to come to his patrol vehicle, and that Mrs. Small had left her vehicle parked on the shoulder of the highway with the gear in “drive” position. Defendant and Mr. Small got out of the car. Trooper Alley ordered them to get back in the car. They did so, but Small *670got in under the steering wheel, shifted the gear from “drive” to “park” and cut off the motor. Trooper Alley testified that “the car moved just a little bit.” Small testified that it did not move. This conflicting evidence raised for jury determination the factual question of whether Trooper Alley had reasonable grounds to believe (probable cause) that Small was driving the motor vehicle. The trial court had the duty of instructing the jury on this question and the factual circumstances that the jury must find in determining whether Trooper Alley was “discharging or attempting to discharge a duty of his office.”
We are aware that G.S. 20-138 (a) has been amended to add “or operate” so that it is now a violation of the statute to drive or operate a motor vehicle on the public highways while under the influence of intoxicating liquor; and we are also aware that G.S. 20-4.01(25) defines an “operator” as “A person in actual physical control of a vehicle which is in motion or has the motor running.” In State v. Turner, 29 N.C. App. 163, 223 S.E. 2d 530 (1976), it was held that where defendant sat behind the steering wheel of a car which had the motor running, the motor stopped, and the car began to roll backward, he was operating the vehicle. However, in the case before us Trooper Alley charged Small with driving the car. He testified that the car moved, and the State based its case on movement of the vehicle. At the close of the State’s evidence, the trial court dismissed the charge against Small of “driving under the influence.” In view of the State’s evidence that Small was in the car on a public highway and was intoxicated, it is reasonable to infer that the ground for dismissal was that the trial judge did not find sufficient evidence to go to the jury on the element of driving a motor vehicle.
It is important that a law-enforcement officer be protected against assault or unlawful resistance while he is discharging or attempting to discharge a duty of his office. It is equally important that members of the public be protected against the illegal deprivation of their liberty by a law-enforcement officer. Where the evidence is so conflicting as to raise the question of whether the law officer is acting lawfully, the jury must be properly instructed by the trial judge.
New trial.
Judges Vaughn and Hedrick concur.