Oregon Revised Statutes Oregon Vehicle Code § 821.202

(1) A person commits the offense of failure of a Class I, Class II, Class III or Class IV all-terrain vehicle operator or passenger to wear a motorcycle helmet if the person is under 18 years of age, operates or rides on a Class I, Class II, Class III or Class IV all-terrain vehicle on premises open to the public and is not wearing a motorcycle helmet with a fastened chin strap.

(2) The requirement to wear a motorcycle helmet with a fastened chin strap does not apply if the all-terrain vehicle is:

(3) The offense described in this section, failure of a Class I, Class II, Class III or Class IV all-terrain vehicle operator or passenger to wear a motorcycle helmet, is a Class D traffic violation.