In court cases there are burden of proofs that must be meet may it be criminal or civil. In a personal injury case (which is considered civil), the person who is making the case (plaintiff) must prove by a preponderance of the evidence that the other person (defendant) is liable. The plaintiff has to show that the harm cased to them was caused because of the defendants actions. The plaintiff must show that the defendant had more than 50% of the fault in the accident. If the jury or judge believes that the fault is split evenly or that the plaintiff is more at fault than the defendant (> 50%) then the plaintiff will be not be awarded anything. However if the jury or judge find the defendant more than 50% at fault then that percent is what the plaintiff can be awarded. For example if a jury find Luis (the plaintiff) to be 20% at fault for the accident and Bob (the defendant) to be 80% at fault, then Luis can only get 80% of the damages and medical bills that he is asking for. So whatever percent of burden of proof the defendant is how much the plaintiff can receive from their total expenses.