“Depending on where you live, this is legal. In at-fault states, insurance companies determine fault based on negligence. This is often decided by a percentage of blame assigned to each driver based on the accident report.
Even if the other driver was 95% at fault, if you were found to be 5% at fault, they could pursue you for 5% of damages. Any time you have some sort of at-fault accident, another driver could pursue legal action.