Originally, the basis for product liability was not the general duty of reasonable care but the duty implicitly undertaken in a contract. Therefore the manufacturer could only be liable to the buyer, who was in privity of the contract, and could not be held liable to other people injured by the defective product. Then, in the case of MacPherson v. Buick Motor Co. (217 N.Y. 382, 111 N.E.1050 (1916)), the wheel of an auto fell off, injuring the owner of the car (MacPherson). Since MacPherson had bought the car from a retailer, and not Buick directly there was no privity. However, the New York Supreme Court changed the law to substitute foreseeability for privity in a contract as a requirement for liability. Prior to this case, the leading case was Winterbottom v. Wright (10 M. & W. 109 (Exch. 1842)), which held that the only people the manufacturer is liable to are people who directly bought their products (that's what privity means). Courts had occasionally allowed for non-privity customers to sue manufacturers, but it had to be an especially egregious case. (see Thomas v. Winchester (6 N.Y. 397 (1852))). If the privity rule had stood, then Buick would only owe liability to the car dealer. That doesn't make a lot of sense. In the old days, most people bought goods directly from the producer, but as society became more complex, and distributors, middlemen, and retailers proliferated, the privity rules had to be discarded in the name of justice. Interestingly, Buick didn't make the defective wheel, it was made by subcontractor. Although this case did away with the requirement for privity, there is still a requirement to show negligence on the manufacturer. (You can still try res ipsa loquitur though.)