Product liability lawsuits don't stop at the manufacturers of products. It extends to the entire chain of distribution. The manufacturer of the product, the company that in turn uses that product to assemble something else, and even the vendor who must exercise great care in offering products for sale. Any one of these individuals could be sued for negligence in a product liability lawsuit. Product liability lawsuits came into being based on the concept that an injured person can sue a negligent person if they are party to the transaction that caused the injury, also called the doctrine of privity. Product liability lawsuits evolved over time based on the erosion of this law. In the case of product liability, the negligent person would be the manufacturer or other person in the chain of distribution. In the beginning, the injured party's only relief would have to be from the seller and the courts could find no wrong with the seller. Eventually, the court system saw the need for the victim to have relief from being injured due to negligence on the part of the manufacturer and so the doctrine of privity began to morph into product liability law.