The worst mistake people make is assuming a dangerous product case only exists if the item was broken. Insurance companies and defense lawyers use that assumption against injured people by arguing the product worked as intended, the user "should have known" the risk, or the warning on the box, insert, or label was enough. What this term really means is that a product can be legally defective when the maker fails to give reasonable warnings, instructions, or safety information about dangers that were known or should have been known.

This matters in injury claims involving medicines, medical devices, fireworks, tools, chemicals, and even equipment in public places. A product may be properly manufactured and still be unreasonably dangerous because the instructions were incomplete, the label minimized the risk, or no warning was given about foreseeable misuse. In a device case, for example, the dispute is often whether the manufacturer adequately warned doctors or users about migration, fracture, burn risk, or the need for monitoring.

In West Virginia, a product liability claim based on inadequate warnings can be reduced or defeated if the defense proves the injured person ignored clear instructions or misused the product. Under the state's modified comparative fault rule, recovery is barred if the injured person is 50% or more at fault. A lawsuit usually must be filed within 2 years of the injury, so preserving packaging, instructions, and recall notices can matter early.