I was in an intersection wreck. I say it was the other guy’s fault. He says it was my fault. Who decides who was at fault?
If a lawsuit is filed a jury usually decides who is at fault (unless a jury is not requested by either party to the case, in which event a judge decides). The jury will listen to your side of the story, the other driver’s side of the story, the testimony of any witness, and review any physical evidence at the scene. Sometimes expert witnesses are hired to explain what happened.
At the end of the day the jury considers all of the evidence, hears the law explained by the judge and uses common sense to decide who probably caused the wreck. Under our system of justice, the person who files a lawsuit only needs to prove that more likely than not the other driver caused the wreck. If the person who files the case is unable to prove that the other driver more likely than not caused the wreck the case will be lost.