What is the initial burden of proving that a product is defective?

Under Barker, in short, the plaintiff bears an initial burden of making "a prima facie showing that the injury was proximately caused by the product's design." (Id. at p. 431.) This showing requires evidence that the plaintiff was injured while using the product in an intended or reasonably foreseeable manner and that the plaintiff's ability to avoid injury was frustrated by the absence of a safety device, or by the nature of the product's design. (See Campbell v. General Motors Corp. (1982) 32 Cal.3d 112, 125-126.) If this prima facie burden is met, the burden of proof shifts to the defendant to prove, in light of the relevant factors, that the product is not defective. Importantly, the plaintiff's prima facie burden of producing evidence that injury occurred while the product was being used in an intended or reasonably foreseeable manner must be distinguished from the ultimate burden of proof that rests with the defendant to establish that its product was not defective because the plaintiff's injury resulted from a misuse of the product.⁶

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