In the presentation and defense of products liability cases, the parties, including plaintiffs and defendants (manufacturers and retailers) often proffer evidence of tests or demonstrations intent on visually proving or disproving a defect claim or causation. The admissibility of this evidence is fact-dependent, predicated upon the nature of the case, the similarity of the test or demonstration to the facts of the case and the purposes for which this evidence is proffered. While courts have drawn distinctions and provided a more permissive standard of review when the test is offered to illustrate scientific principles rather than a representation of the incident or event, that distinction is easily blurred when the generic representation gets "close to the facts of the case." Whether you want to offer into evidence a test or demonstration as part of the plaintiff's case in chief or in defense of a products liability case, the following legal analysis must be accounted for—before spending the time and expense.