The level of care or duty owed varies by state. Many states impose a duty to exercise a high degree of care in dealing with firearms. Other states impose a duty of ordinary care, but say that the standard of care is the care ordinarily used when dealing with firearms. In addition, there are federal, state, and local laws, which may impose a duty on the owner, seller or distributor of firearms. Such laws may forbid sales of weapons to certain classes of people, such as felons, minors and incompetents.

Once it is established what, if any, duty was owed, the question becomes whether that duty was breached. If the defendant violated the law, the court will look at whether the victim was in the class of people meant to be protected by the law, and whether the harm done to the victim was the sort of harm the law was designed to prevent. If the law was intended to prevent the type of harm caused to persons such as plaintiff, then the majority of courts will hold that the defendant is "negligent per se" or, negligent as a matter of law. Thus, violation of the law would be conclusive proof of negligence and the only question would be whether the negligence caused the plaintiff 's damages.

Firearm Liability: Proving Fault in Negligence Cases

As noted above the fact that a defendant is negligent with respect to a weapon does not mean that the plaintiff automatically recovers. The plaintiff must still show that the negligence caused his or her injury. This is called showing causation. Showing causation requires proof of two related things. First, the plaintiff has to show that the defendant's act or omission (the breach of duty) was the actual cause of the injury and the plaintiff must show that there is a reasonable connection between the defendant's negligence and the plaintiff's injuries. For example, if a parent buys his seventeen-year-old child a gun in violation of federal, state, and local law, he may be negligent. But, if the gun is not the cause of injury until twenty years later, the connection between the negligence and the injury may be too remote, even though the negligently purchased gun was the actual cause of the injury.