Cal. Vehicle Code - VEH § 21300. Section 21300.
(a)
A person under 18 years of age shall not ride an equestrian animal upon a paved highway unless that person is wearing a properly fitted and fastened helmet that meets the standards of either the American Society for Testing and Materials or the United States Consumer Product Safety Commission, or standards subsequently established by those entities.
(b)
A person riding an equestrian animal upon a paved highway during hours of darkness, as defined in Section 280, shall do one of the following:
(1)
Wear reflective gear or have reflective gear on the equestrian animal that shall be visible from a
distance of 500 feet on the rear and the sides when directly in front of the lawful upper beams of headlamps on a motor vehicle.
(2)
Have a lamp emitting a white light attached to either the person or the equestrian animal that is visible from a distance of 300 feet in front of and from the sides of the equestrian animal.
(c)
Notwithstanding subdivisions (a) and (b), a person is not required to wear a helmet or reflective gear while riding an equestrian animal when participating in a parade or festival, or while crossing a paved highway from an unpaved highway.
(d)
In a civil action, a violation of subdivision (a) or (b)
does not establish negligence as a matter of law or negligence per se for comparative fault purposes, but negligence may be proven as a fact without regard to the violation.
(e)
A charge under this section shall be dismissed when the person charged alleges in court, under oath, that the charge against the person is the first charge against that person under this section, unless it is otherwise established in court that the charge is not the first charge against the person.
(f)
(1)
Except as provided in subdivision (e), a violation of this section is an infraction punishable by a fine of not more than twenty-five dollars ($25).
(2)
The parent or legal guardian having control or custody of an
unemancipated minor whose conduct violates this section shall be jointly and severally liable with the minor for the amount of the fine imposed pursuant to this subdivision.