Torts Deep Dive: Products Liability — How to Spot Strict Liability, Negligence, and Warranties
Products liability is one of the most cross-tested Torts topics. One defective product can trigger three distinct causes of action — Strict Products Liability, Negligence, and Breach of Warranty.
If you’ve already studied Negligence — the law of carelessness and Intentional Torts — the law of purpose and control, this post completes the trilogy. Together, they form the foundation of all tort analysis: intent, carelessness, and product safety.
The facts won’t tell you which theory to use — your analysis will.
Why Products Liability Is So Common
If you see a defective consumer product on an exam — a tire blowout, exploding coffee maker, or malfunctioning medical device — Products Liability is in play.
Bar examiners love it because it tests your ability to separate three overlapping theories: strict liability, negligence, and warranty.
The question is never just “Who was hurt?” — it’s “Why is that party responsible?”
The Three Theories at a Glance
There are three major analytical routes in products liability:
1. Strict Products Liability (Torts):
Focuses on the product itself.
Ask: Was the product defective and unreasonably dangerous when sold?
2. Negligence (Torts):
Focuses on the manufacturer’s conduct.
Ask: Did the defendant act unreasonably in designing, inspecting, or warning?
3. Breach of Warranty (Contracts / UCC):
Focuses on the promises about the product.
Ask: Did the product fail to conform to an express or implied warranty?
Strict Products Liability: The Core Rule
A commercial supplier is strictly liable for selling a product in a defective condition unreasonably dangerous to the user or consumer if the product reaches the consumer without substantial change and causes injury when used in a foreseeable way.
You don’t have to prove fault, intent, or privity. The question is the condition of the product — not the conduct of the manufacturer.
The Three Strict Liability Defect Theories
1. Manufacturing Defect
The product departs from its intended design — a one-off production flaw. The product is more dangerous than intended because of a mistake in assembly, materials, or workmanship.
Example: A single space heater in a batch has a loose internal wire that causes a fire.
2. Design Defect
The product was built as intended — but the design itself is unsafe.
Two main tests:
- Consumer Expectation Test: The product is more dangerous than an ordinary consumer would expect.
- Risk-Utility Test: The danger outweighs its usefulness, and a safer alternative design was feasible.
- Example: A heater lacks an automatic shutoff feature even though a simple switch could prevent fires.
3. Failure to Warn (Marketing Defect)
The product lacks adequate warnings or instructions about non-obvious risks.
If foreseeable risks could have been reduced or avoided with reasonable warnings, the product is defective.
Example: The manual fails to warn that plugging the heater into an extension cord can cause fires.
The Hypo
P buys a portable space heater from a local hardware store. After a week of normal use, the heater catches fire, igniting nearby curtains and causing burns. Investigation shows a loose wire caused the short-circuit.
This one paragraph triggers all three legal theories.
Application: Walking Through the Theories
Strict Products Liability
P starts here. The manufacturer and retailer are commercial suppliers. The heater was defective when sold and reached P without alteration.
The loose wire shows a manufacturing defect, but a poor wiring layout could be a design defect, and lack of warnings could be a failure-to-warn defect.
Defendants will argue product misuse, alteration, or assumption of risk. Strict liability doesn’t require fault — but these defenses can reduce or bar recovery.
Negligence
Negligence focuses on the conduct, not the product.
P argues the manufacturer breached its duty of reasonable care in designing or inspecting the heater. A reasonable manufacturer would have discovered the loose wire.
D argues it met all safety standards and could not have foreseen the failure. Comparative fault and contributory negligence apply as usual.
Breach of Warranty
If the heater was sold as “safe for indoor use,” that’s an express warranty.
If sold by a merchant, it also carries an implied warranty of merchantability (fit for its ordinary purpose).
If the seller knew P relied on its advice (“safe to run overnight”), that creates an implied warranty of fitness for a particular purpose.
When the heater caught fire, all warranties were breached.
Defenses like disclaimer, notice, and lack of privity may limit recovery.
Defenses Across Theories
Even when a product is defective, each theory has its own defenses. Knowing which apply where separates a passing essay from a top-scoring one.
Defenses to Strict Products Liability:
- Product Misuse: Using the product in an unforeseeable way (e.g., wrapping cords around the heater) may bar recovery. Foreseeable misuse, however, does not.
- Assumption of Risk: If P knew of the defect and used the product anyway, recovery is barred (e.g., ignoring a known recall).
- Comparative Fault: Some jurisdictions allow comparative fault to reduce damages (e.g., ignoring clear warnings).
- Substantial Change: If the product was materially altered after sale, strict liability fails (e.g., rewiring the heater).
Defenses to Negligence:
- Contributory or Comparative Negligence: P’s own negligence, like ignoring safety instructions, can reduce or bar recovery.
- Assumption of Risk: P knew the product was defective but used it anyway.
- Superseding Cause: An unforeseeable third-party act, like a power surge, breaks causation.
Defenses to Breach of Warranty:
- Disclaimer of Warranties: Sellers can disclaim implied warranties (“as is”) if done clearly and conspicuously. Express warranties cannot be disclaimed.
- Failure to Give Notice: Buyers must notify the seller of breach within a reasonable time after discovery.
- Lack of Privity: Some jurisdictions still require a direct buyer-seller relationship.
- Limitation of Remedies: Contracts may limit remedies to repair or replacement, unless the limitation is unconscionable or fails its essential purpose.
Putting It All Together
A top essay distinguishes the three theories and their defenses:
- Strict Liability: Focus on the defective product and defenses like misuse and assumption of risk.
- Negligence: Focus on unreasonable conduct and apply traditional negligence defenses.
- Warranty: Focus on promises and apply contract defenses like disclaimer and notice.
The best essays analyze all three theories and compare them directly — showing that you can reason by product, conduct, and promise.
Pro Tips
- Always identify whether the defect is manufacturing, design, or failure to warn.
- Pair every theory with its correct defenses.
- Mention foreseeable use and foreseeable misuse.
- Strict Products Liability = Product Focus.
- Negligence = Conduct Focus.
- Warranty = Promise Focus.
FAQ
1. What’s the difference between strict liability and negligence?
Strict liability focuses on the defective product; negligence focuses on the manufacturer’s conduct.
2. Can retailers be liable under strict liability?
Yes — any commercial seller in the distribution chain can be strictly liable.
3. What are the three types of defects?
Manufacturing defect, design defect, and failure to warn.
4. What defenses apply to strict liability?
Product misuse, assumption of risk, comparative fault, and substantial change.
5. What defenses apply to warranty?
Disclaimers, lack of notice, and lack of privity — all contractual defenses.
