Abstract: A safety system for an electrically drivable motor vehicle includes a primary braking system, a secondary braking system, and a tertiary braking system. The system includes a monitoring device configured to detect an operating error in the primary and/or secondary braking systems, a detection unit configured to acquire motor vehicle data, and an evaluation unit configured to assess an achievable deceleration potential of the tertiary braking system using the motor vehicle data. A comparison unit compares the evaluated deceleration potential to at least one defined safety criterion, and a control unit controls the motor vehicle based on the detection of an operating error and/or the comparison result. Also described are methods for operating the safety system, including recognizing an operating error, acquiring motor vehicle data, evaluating the deceleration potential, comparing the deceleration potential to a safety criterion, and controlling the motor vehicle based on these steps.