In most cases, if a driver backs into a legally parked car, they are usually found to be at fault for the accident. This is because it is the responsibility of the driver to ensure that they have a clear path before backing up.
However, if a driver backs into an illegally parked car, fault may be shared between the two parties. While the driver of the moving vehicle still has a duty to exercise caution when backing up, the driver of the illegally parked car may also be found to be partially responsible for the accident by obstructing the flow of traffic.
Ultimately, the determination of fault in an accident involving a parked vehicle will depend on the specific facts and circumstances of the case. Factors such as the location of the parked vehicle, the visibility, and the actions of both drivers will be taken into account.
In some cases, the laws governing parking regulations and the duties of drivers backing up may vary by jurisdiction. It is important to consult with local laws and regulations to determine the specific rules and regulations that apply in a particular area.