Speak with your insurance company regarding filing an uninsured or underinsured motorist claim. If the at-fault party doesn't have car insurance, you can still file a claim for compensation under your own uninsured motorist policy with your insurer.Uninsured Motorist Coverage: First, check if your own car insurance policy includes uninsured motorist (UM) coverage. Injury; Monetary loss; Pain and suffering; Property damages. In such a case, an Arizona court would determine how much of the accident is each driver's fault. The process of suing an underinsured motorist in Arizona begins with filing a claim with their insurance company. If you're involved in a highway accident with an uninsured or underinsured motorist, the claims process can become more complicated. What Are Some Auto Accident Statistics in Arizona? Phoenix drivers are often distraught when they find out that despite the law, the other driver does not have coverage and a way to compensate them. Arizona law recognized the concept of "comparative fault" which means that both parties may be partially at fault for an accident.