The Hours of Service (HOS) rule in California is a set of regulations that dictate how many hours a commercial driver can operate a commercial vehicle and how many hours of rest they must have between shifts. In California, commercial drivers are subject to the federal HOS regulations, which require drivers to take a 30-minute break after 8 hours of driving and limit driving time to 11 hours per day and 70 hours per week. Additionally, drivers must have at least 10 consecutive hours off-duty before beginning a new shift. These regulations are designed to prevent driver fatigue and reduce the risk of accidents caused by tired drivers.