Products Liability

The Five Theories and the Three Defects

A plaintiff injured by a product may sue on five theories, and a strong essay canvasses each: (1) negligence, (2) strict products liability, (3) implied warranty of merchantability (and fitness for a particular purpose), (4) express warranty, and (5) intentional/negligent misrepresentation. Each has distinct elements, defendants, and defenses, but most share a common factual core: a defective product caused harm.

There are three types of defect across all theories:

Manufacturing defects are the easiest for plaintiffs: the product is compared to the manufacturer's own design, and any deviation that makes it more dangerous suffices. Design defects and warnings are litigated harder because the plaintiff attacks the whole product line or the adequacy of instructions.

California's foundational role: California created strict products liability in Greenman v. Yuba Power Products Co. (1963), holding that a manufacturer is strictly liable when an article it places on the market, knowing it will be used without inspection, proves to have a defect that causes injury. The doctrine spread nationwide via Restatement (Second) § 402A.

Strict Products Liability Elements and California's Design-Defect Tests

Prima facie strict products liability requires:

1. The defendant is a commercial seller of the product (manufacturer, distributor, or retailer in the business of selling such goods — NOT a casual/one-time seller);
2. The product was defective (manufacturing, design, or warning) when it left the defendant's control;
3. The product reached the plaintiff without substantial alteration;
4. The defect was the actual and proximate cause of injury; AND
5. The plaintiff suffered damages while making a foreseeable use (including foreseeable misuse) of the product.

No privity required. Any commercial seller in the distribution chain is liable, and any foreseeable plaintiff — buyer, user, or even a bystander — may recover. A retailer with no fault can be held strictly liable (and seek indemnity up the chain). Note that service providers and casual sellers are generally not subject to strict products liability.

California's two design-defect tests (Barker v. Lull Engineering Co., 1978): A plaintiff may establish a design defect under either:

• The consumer-expectation test: The product failed to perform as safely as an ordinary consumer would expect when used in an intended or reasonably foreseeable manner. (Best for products whose ordinary use produces clear safety expectations.)
• The risk-benefit test: The benefits of the challenged design are outweighed by the risk of danger inherent in that design. Critically, once the plaintiff shows the design proximately caused injury, the burden SHIFTS to the defendant to prove the benefits outweigh the risks (considering gravity of danger, likelihood of harm, feasibility of a safer alternative design, financial cost, and adverse consequences of an alternative).

The burden-shifting of Barker's risk-benefit prong is a defining California distinction — note it on any California design-defect essay. (For complex products beyond ordinary consumer experience, courts may require the risk-benefit test rather than consumer expectations.)

Warning Defects, Warranty Theories, and Defenses

Warning defects: A product is defective if it carries non-obvious dangers that could be reduced by adequate warnings or instructions, and the seller failed to provide them. The danger must be one the seller knew or should have known about. Learned-intermediary rule: for prescription drugs and medical devices, the manufacturer's duty to warn generally runs to the prescribing physician (the learned intermediary), not directly to the patient. Obvious dangers (a knife is sharp) need no warning.

Warranty theories:

• Implied warranty of merchantability (UCC § 2-314): Goods sold by a merchant must be fit for their ordinary purpose. Breach is essentially strict liability in contract; privity rules are relaxed and personal-injury plaintiffs may recover.
• Implied warranty of fitness for a particular purpose (§ 2-315): Arises when the seller knows the buyer's particular purpose and the buyer relies on the seller's skill.
• Express warranty (§ 2-313): Any affirmation of fact or promise about the goods that becomes part of the basis of the bargain. Breach is strict.
• Misrepresentation: A seller is liable for material misrepresentations of fact about a product on which the plaintiff justifiably relied (intentional, negligent, or even innocent in some formulations under § 402B).

Defenses (California, pure comparative fault):

• Comparative fault reduces recovery: a plaintiff's unreasonable failure to discover a defect or unreasonable use diminishes damages (Daly v. General Motors).
• Assumption of risk (knowingly using a product known to be defective) reduces or bars recovery.
• Product misuse that is unforeseeable defeats the claim — but foreseeable misuse does not.
• Substantial alteration by a third party after sale can break causation.
• State-of-the-art evidence (the danger was scientifically unknowable at the time) is relevant to design and warning claims.

MBE trap: A plaintiff need not be the purchaser — bystanders recover in strict liability. And a faultless retailer IS liable in strict products liability even though it could not have discovered the defect; that is the point of strict liability (the retailer's remedy is indemnity against the manufacturer).