Product liability cases fall into three distinct categories based on what went wrong with the product: design defects, manufacturing defects, and warning defects. Understanding these categories helps injured consumers identify the strongest legal theory for their particular situation and shapes the evidence needed to prove their case.
Design Defects: Fundamentally Flawed Products
A design defect exists when the product's fundamental design makes it unreasonably dangerous, regardless of how carefully individual units are manufactured. Every product built according to a defective design shares the same flaw. The problem is not that something went wrong during production—the problem is that the design itself creates unacceptable risks.
Classic design defect cases have involved vehicles with fuel tank placements that caused fires in rear-end collisions, children's products with small parts that posed choking hazards, and medical devices that released toxic materials into patients' bodies. In each instance, the danger affected all units of the product, not just specific items that deviated from specifications.
Courts evaluate design defects using different tests depending on jurisdiction. The consumer expectations test asks whether the product failed to perform as safely as an ordinary consumer would expect. The risk-utility test weighs the product's benefits against its dangers, considering whether a safer alternative design was feasible. Under either analysis, manufacturers may be liable for designs that create unreasonable risks of harm.
Manufacturing Defects: When Production Goes Wrong
Manufacturing defects occur when something goes wrong during the production process, causing specific products or batches to deviate from their intended design. Unlike design defects affecting all units, manufacturing defects may affect only certain products while leaving others perfectly safe. The design was sound, but execution failed.
Manufacturing defects arise from various sources: contamination during production, improper assembly, substitution of substandard materials, inadequate quality control, and equipment malfunctions that alter products from their specifications. A product may be perfectly designed yet become dangerous if the manufacturing process introduces flaws.
Proving manufacturing defects typically requires comparing the defective product to its design specifications and demonstrating deviation. Expert analysis of the failed product often reveals telltale signs of manufacturing problems that would not exist in properly produced units. The manufacturer is strictly liable for such defects regardless of how much care was exercised during production.
Warning Defects: The Failure to Inform
Even properly designed and manufactured products can give rise to liability when manufacturers fail to provide adequate warnings about foreseeable risks. Products that are unavoidably dangerous when used as intended may still be legally sold if adequate warnings allow consumers to make informed decisions and take appropriate precautions.
Failure to warn claims arise when manufacturers know about product risks but fail to communicate them effectively. Warnings may be inadequate because they omit known dangers, fail to convey the severity of risks, are not prominently displayed, or do not reach the people who need the information. When inadequate warnings contribute to injuries, the manufacturer bears responsibility.
In prescription drug and medical device cases, the learned intermediary doctrine often applies, meaning manufacturers satisfy warning duties by informing prescribing physicians rather than patients directly. However, this doctrine has limits and does not protect manufacturers who fail to provide adequate information to healthcare providers.
Multiple Defect Theories
Many product liability cases involve more than one type of defect. A product might have both a design flaw and inadequate warnings about resulting risks. Pursuing multiple theories strengthens claims by providing alternative paths to recovery and guards against defenses that might defeat individual theories. An experienced product liability attorney can evaluate which defect categories apply to particular cases and develop appropriate litigation strategies.