California Code, Public Utilities Code - PUC § 7654

Every railroad corporation shall print and conspicuously post on the inside of its passenger cars its rules and regulations regarding fare and conduct of its passengers. In case any passenger is injured on or from the platform of a car, or on any baggage, wood, gravel, or freight car, in violation of such printed regulations, or in violation of positive verbal instructions or injunctions given to the passenger in person by any officer of the train, the corporation is not responsible for damages for the injuries, unless the corporation has failed to comply with the provisions of Section 7653.