The issue in a used gun case is whether the seller had control over how the buyer used the gun and if the buyer took an unreasonable risk. The Doctrine of Assumption of Risk absolves a defendant of liability for creating an unreasonable risk. An individual does not assume the risk of harm from another's conduct unless they know of the risk and appreciate its unreasonable character. Many states have replaced the Doctrine of Assumption of Risk with contributory negligence, where a judge or jury decides fault based on evidence. Thus, one should be cautious when dealing with a used gun case.