Abstract: A method and system for preventing use of a vehicle by an operator of the vehicle. The system includes a system controller; a biometric authenticator coupled to the system controller; and a substance detecting device adapted to provide a substance level in the operator to the system controller. Here, the system controller is adapted to communicate a driving restriction to the vehicle if the substance level in the operator is above a tolerance level or if the operator is not authenticated by the authenticator, the substance level is determined at an extremity of the operator, the operator is also authenticated at the extremity, and the extremity is selected from the group consisting of finger, thumb, toe, ear, palm, sole, foot, hand, and head.