Consumer expectations test
In legal disputes regarding product liability, a consumer expectations test is used to determine whether the product is negligently manufactured or whether a warning on the product is defective. Under this test, the product is considered defective if a reasonable consumer would find it defective. As an example, a reasonable consumer might find exposed blades on a lawnmower, without plastic guards that could be installed for pennies, to be defective because the risk of not having the plastic guards is higher than the costs of installing those guards.
The test is mostly applied to non-complex products about which consumers might have expectations. For example, the consumer might not have specific safety expectations about the design of landing gear on an airplane except for the fact that they do not expect to crash while taking the plane.
A closely related test is risk-utility test. Traditionally, the risk-utility test was used for design defects, while the consumer expectation test was applied to manufacturing defects. However, some jurisdictions apply the consumer expectation test to design defects as well. See Calles v. Scripto-Tokai Corp., 2007 WL 495315 (Ill. Feb. 16, 2007).
Official definition of consumer expectation test: An unreasonably dangerous product is one that is dangerous to an extent beyond that which would be contemplated by the ordinary consumer who purchases it, with the ordinary knowledge common to the community of its characteristics.
This test is commonly applied in product liability cases in the United States.
In the European Union, the European Council Directive on General Product Safety 2001/95/EC states (at Article 3(f)) that the conformance of a product to a general safety requirement shall be assessed taking into account "reasonable customer expectations regarding safety" (amongst other considerations).