California Code, Vehicle Code - VEH § 27319

(a) If a bus is equipped with a driver safety belt, the driver of the bus shall not operate the vehicle unless he or she is properly restrained by the safety belt.

(b) If a bus is equipped with a driver safety belt, the motor carrier shall maintain the safety belt in good working order for the use of the driver.

(c) Notwithstanding subdivision (a) of Section 42001, a violation of this section is an infraction punishable by a fine of not more than twenty dollars ($20) for a first offense and a fine of not more than fifty dollars ($50) for each subsequent offense.

(d) The requirements of this section are intended to satisfy the requirements of Section 392.16 of Title 49 of the Code of Federal Regulations, or any similar federal law or regulation, but shall remain in effect in the absence of those laws.

(e) This section shall be operative July 1, 2018.