That's why I have two, normal front facing and also one on the rear liftgate window. If I am at fault, like a few months ago when I got my first ticket in 25 years by missing the reduced speed sign at the start of a new construction zone along my daily commute, at least I know for sure and don't feel bad about paying the appropriate penalty. But if it turns out that I am not at fault, there's at least some evidence that may help. Of course, some people turn a blind eye to what they don't want to admit. Unfortunately, this can also include insurance companies and the legal system. So it's no guarantee.