Well if you were backing in and hit someone then it is your fault. But if they hit you, then it is their fault.
If you are driving the backing car, no matter WHERE the other cas is located, YOU are the one at fault if you collide with it.
If you were both backing out at the same time, then it will be considered joint fault, sometimes called contributory negligence. That means both drivers failed to notice the other driver.
The person who is backing out of the parking space
Both of you are probably at fault. If you see another person backing you should stop and signal the other driver if possible. Otherwise stop and wait until that driver completes his backing maneuver.Added: It is the obligation of the backing driver to ascertain that his movement does not interfere with any other vehicles. In this instance, you both apparently failed to do so.
The person backing up. That is, unless the other person had a clear chance to avoid the accident and failed to do so (i.e., wasn't paying attention).
The person backing out. If you were in the lane/road behind them they needed to use caution when backing out.
It is the other person's fault because they had to have seen you pulling in first. They were being greedy.
The driver backing up. Unless you can prove the other car was driving unsafly.
Any time the driver who is backing is at fault, in all 50 states.
both of you for not looking back
Backing up--it is your fault.