Cases in which this can happen. - I orient myself before overtaking another car on the highway or motorway. - I position my hand wrong on the steering wheel and the camera can no longer see me. - I put on sunglasses when I am driving against a low sun.
It can be turned off, but if you live in the EU it is required to enable itself once the car has been turned off/on.
It will also happily warn me if it thinks I am speeding based on errornous gps data. This feature also turns itself back on once the car has been turned off.