Negligent entrustment is a cause of action in United States tort law which arises where one party ("the entrustor") is held liable for negligence because they negligently provided another party ("the entrustee") with a dangerous instrumentality, and the entrusted party caused injury to a third party with that instrumentality. The cause of action most frequently arises where one person allows another to drive their automobile. General principles One of the earliest reported cases under this cause of action, the 1915 Mississippi case of Winn v. Haliday, concerned the negligence of the father in entrusting a dangerous agency to a son known to be negligent, based on the allegation that the appellant knew his son to be given to 'joyriding'. The key allegation that must be proven in such a case can be described as follows: A plaintiff who invokes that doctrine must present evidence which creates a factual issue whether the owner knew, or had reasonable cause to know, that he was entrusting his car to an unfit driver likely to cause injury to others. Furthermore, in order to impose liability upon the owner, the plaintiff must prove that the negligent entrustment of the motor vehicle to the tortfeasor was a proximate cause of the accident. Negligent entrustment is generally found where the entrustee had a reputation or record that showed his propensity to be dangerous through possession of such an instrumentality. Where the claim is against an employer, the employer will be held liable if the entrustee's record was known to the employer or would have been easily discoverable by that employer, had a diligent search been conducted. For example, suppose a bus company hires a driver who has a record of reckless driving, which the company could have learned of through a search of publicly available records. The company will be liable for the negligent entrustment of the bus to that driver, if the driver is in an accident. Similarly, if A lends his handgun to B, knowing that B has a propensity for violence, A may be held to have negligently entrusted the gun to B when B uses the gun to shoot someone during an argument. However, such cases are often harder to prove than negligent entrustment cases involving employment, because judges and juries are less likely to find that an entrustor had a duty to check on the publicly available records of an entrustee who