RS 45:189 - Speedometer required; unlawful speed prima facie evidence of negligence Every service car shall be supplied and equipped with a speedometer in open view and when any service car is being driven at an unlawful speed, and an accident or a mishap occurs which results in the death of, or injury to, any passenger, such unlawful speed shall be prima facie evidence that the accident or mishap was occasioned by, or resulted through, the negligence of the operator of the service car.
Louisiana Legal Code