fixing sensor

That is being developed right now, using radar technology.

It will work well on a test bench right now, but when it is installed in a production car, if it should malfunction, the results could be fatal, and the law suit would be sure to follow.

This was my thought as well, way back when ABS on cars was new. But ABS has been successfully installed on almost all vehicles, with no lawsuits of which I am aware. I believe that the same approach will work here.

The collision avoidance system (CAS) will continuously self-test, and if it fails, a dashboard light will indicate failure status, and then it is on the driver. This is easier than ABS: with brakes, you had to ensure that the brakes failed safe (default to normal braking, not complete loss of brakes). Whereas with CAS there is no tie-in to a safety-critical system; it is extra information only.