Practice Tip: Mounting an Effective Defense to Use of the 'Malfunction Theory'

Decades ago, American jurisprudence began blurring the lines between classic strict liability and negligence principles in product liability lawsuits. The lines initially were blurred with the application of res ipsa loquitur principles to liability issues and with the application of comparative fault principles to damage issues. In many jurisdictions today, those lines are not merely blurred but have overlapped. Focusing on liability issues, this overlap has occurred with the increasingly widespread acceptance of circumstantial evidence ' in certain cases ' to establish the existence of a defect. This doctrine has been called the “malfunction theory,” the “indeterminate defect theory” or simply has been referred to as the application of res ipsa loquitur or circumstantial evidence principles to product liability cases. Perhaps the most potent harbinger that the malfunction theory is here to stay is its 1998 incorporation into the Products Liability Restatement '3.

Application of the malfunction theory allows a plaintiff to establish the existence of a defect by relying on circumstantial evidence when proof of a specific defect is unavailable. In essence, it broadens a plaintiff's ability to establish a strict liability case by allowing the plaintiff to prove the incident that caused the alleged harm 1) was of a kind that ordinarily occurs as a result of product defect, and 2) was not, in the particular case, solely the result of causes other than product defect existing at the time of sale or distribution. It does not eliminate the traditional strict liability elements the plaintiff is required to prove, such as the existence of a defect, damages, proximate cause, and that the defect existed at the time it left the manufacturer's control. Rather, the malfunction theory provides an alternate method by which a plaintiff can prove the existence of a defect.