Defective product liability is based on a theory of legal responsibility that varies from state to state. The newest - and increasingly, the most common - legal theory underlying products liability law is strict liability. When this legal theory is applicable, the manufacturer, distributor, and/or seller of a product is liable for the injuries caused by the product and suffered by the consumer, regardless of the circumstances. There need be no showing of intent or careless behavior on the part of the manufacturer in order to maintain a products liability case under a theory of strict liability; rather, if the consumer can show that he or she was injured by a defective product, then the manufacturer or other relevant party is automatically liable for those injuries. The consumer's only burden is to prove that the product had a defect, which is a more expensive term than one might think. When a product is defective, it is said to be unreasonably dangerous for its intended usage.