When a product malfunctions due to a defect and causes serious personal injury, the law requires the manufacturer, wholesaler or retailer of the product to bear the losses caused by the defect in the product. Almost thirty million injuries and over 20,000 deaths are caused each year by defective or unsafe products, including such everyday items as hairdryers, toasters, baby chairs, air conditioners, automobiles and hand tools. The claims for a defective product can be based on negligence, strict liability and breach of warranty. Strict liability is a term that means a defendant may be responsible even if the defendant was not negligent. Under the strict products liability law that has developed under the common law in New York, a manufacturer and seller will be held liable even if they were not negligent if the product was in fact defective. Failure to warn of dangerous propensities, or failure to give adequate instructions for the safe use of the produce may also be defects. If the defect in the product causes a user to suffer damages, the policy of the law is to take that loss off of the shoulders of the innocent user and place it back to the manufacturer who will then be in a position to spread the loss by including it as a cost of the product. In that way an individual who may suffer catastrophic losses will be compensated and the cost will be shared by all users of the product as the manufacturers' cost of doing business. This policy also is an incentive to the manufacturer to correct defects in its product line.

A product liability claim may also be based on a breach of warranty under the law of contracts. The Uniform Commercial Code which governs commercial transactions in the United States includes warranties of merchantability and fitness for a particular purpose. If a product does not meet this standard then the manufacturer and seller will be liable for the loses sustained by the user. For example if a chair collapses under ordinary circumstances it is not fit for its purpose and the manufacturer will be responsible for reimbursing the injured victim.

A manufacturer may also be held responsible for ordinary negligence in manufacturing and designing a product.

In products liability cases the product itself is the most import evidence and the product should be stored in a secure location and kept in the your custody if possible. It will be necessary for engineers and other expert witnesses to thoroughly evaluate the product.