If the driver just pulled out in front of you it’s their fault. If they were on the road and you just rammed them because you couldn’t stop safely within the distance you could see up the road, then it’s your fault, and you whining to the judge that you were doing the speed limit isn’t going to go far. Seriously, how did you pass the written drivers test? This isn’t a complicated concept.
Yes, it is complicated.
Here are legal and valid exemptions/defenses for fault in a rear-end collision.
Improper lane change or failure to yield.
Affirmative testimony regarding a mechanical failure.
Affirmative testimony of a sudden and unexpected stop or unexpected lane change by the car in front.
When a vehicle has been illegally and, therefore, unexpectedly stopped.
A vehicle backs into your car.
Seriously, how did you pass the written drivers test?