legal concept or doctrine that holds manufacturers or sellers responsible, or liable, for harm caused by defective products sold in the marketplace. Manufacturer's liability is usually determined on any of three bases: (1) negligence, which is the failure to exercise reasonable care to prevent product defects arising out of the manufacturing process, or which is the failure to give consumers appropriate warning of a danger attending the use of a manufactured product, (2) breach of warranty, which entails failure to fulfill the terms of a claim or promise concerning the quality or performance of a particular product, and (3) strict liability, in which a seller or manufacturer can be held liable for a defective product even if the conditions of negligence or breach of warranty do not apply. An active consumerism movement is credited with the courts' increasing acceptance of arguments based on manufacturer's liability.