In some car accidents, liability is easy to determine. When another motorist runs a red light and hits you (or fails to stop and rear-ends you at a stop sign), the police report and eyewitness testimony are usually enough to prove fault. Sometimes, though, car accidents are more complicated and require an in-depth investigation to determine liability and collect the evidence to prove fault. To win compensation for your injuries, we must prove negligence. We need to show the other motorist acted carelessly.