Strict liability and products liability - Defenses to such c...

Learning Outcomes

This article outlines the core defenses available in strict liability and products liability actions and how they are tested on the MBE. It distinguishes defenses that turn on the plaintiff’s conduct—comparative fault, contributory negligence, and express or implied assumption of risk—from defenses focused on the nature or use of the product, including foreseeable versus unforeseeable product misuse, substantial alteration or modification, and adequate warnings or instructions. It also outlines doctrine unique to design defect and failure‑to‑warn cases, such as the state‑of‑the‑art defense, government compliance, and federal preemption of certain state tort claims. The article explains how contractual concepts like disclaimers, remedy limitations, and warranty notice requirements interact with, but generally do not defeat, strict products liability in tort. The discussion emphasizes exam skills: spotting the governing theory (strict liability, negligence, or warranty), matching the correct defense to that theory, and determining whether the defense operates as a complete bar to recovery, a partial reduction of damages, or merely supporting evidence on defectiveness. These outcomes enable systematic evaluation of MBE fact patterns involving abnormally dangerous activities, animals, and defective products.

MBE Syllabus

For the MBE, you are required to understand the defenses that can be raised against claims based on strict liability (for abnormally dangerous activities or animals) and products liability (whether based on strict liability, negligence, or warranty), with a focus on the following syllabus points:

• Apply comparative fault principles (including contributory negligence where specified) in the context of strict liability and products liability actions.
• Analyze whether the plaintiff assumed the risk associated with the dangerous activity or defective product.
• Determine if a product was misused in an unforeseeable manner.
• Assess the effect of adequate warnings or instructions provided with a product.
• Understand the state-of-the-art defense, particularly in design defect cases.
• Recognize the limited applicability of disclaimers in strict products liability tort actions versus warranty actions.
• Identify situations involving federal preemption of state tort claims regarding product safety standards.
• Distinguish the availability of these defenses in strict liability claims for abnormally dangerous activities or animals from their use in negligence-based products liability suits.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. A driver knowingly operates a car with brakes she knows are faulty. While driving carefully, the brakes fail, and she hits a pedestrian. The jurisdiction follows traditional contributory negligence rules but applies comparative fault to strict products liability claims. If the pedestrian sues the car manufacturer under strict products liability, and the manufacturer proves the driver was negligent, what is the likely effect of the driver's negligence on the pedestrian's claim?
   1. It will completely bar the pedestrian's recovery.
   2. It will reduce the pedestrian's recovery based on the driver's percentage of fault.
   3. It will have no effect on the pedestrian's recovery.
   4. It will be relevant only if the driver is also sued.
2. A consumer buys an electric knife. The instructions clearly state, "Do NOT use near water." The consumer uses the knife while standing barefoot in a puddle of water, receives an electric shock, and is injured. In a strict products liability suit against the manufacturer, which defense is most likely to succeed?
   1. Comparative fault.
   2. Assumption of the risk.
   3. Product misuse.
   4. State-of-the-art.
3. A pharmaceutical company markets a drug approved by the FDA with warnings about potential side effects based on known research at the time of approval. Years later, new research reveals a previously unknown, serious risk. A patient injured by this newly discovered side effect sues the company under strict products liability for failure to warn. Which defense is the company most likely to raise successfully?
   1. Federal preemption.
   2. State-of-the-art.
   3. Assumption of the risk.
   4. Product misuse.

Introduction

Defendants facing claims grounded in strict liability, whether for abnormally dangerous activities, animals, or defective products, are not without recourse. While the “strict” nature of the liability means the plaintiff generally does not need to prove fault, certain defenses focusing on the plaintiff’s conduct or the nature of the product and its use can bar or reduce recovery. Understanding these defenses is essential for analyzing liability scenarios accurately. These defenses often overlap with those available in negligence actions but may be applied differently in the strict liability context.

On the MBE, you must be able to separate:

• Defenses to strict liability for abnormally dangerous activities and animals (where the conduct itself is not negligent but extraordinarily risky).
• Defenses to strict products liability (defective manufacture, design, or warnings).
• Defenses unique to warranty-based or negligence-based products liability claims.

Key Term: Strict Products Liability
A tort theory under which a commercial seller is liable for harm caused by a defective and unreasonably dangerous product, regardless of the seller’s exercise of reasonable care.

Key Term: Abnormally Dangerous Activity
An activity that creates a foreseeable and highly significant risk of physical harm even when reasonable care is exercised, and that is not a matter of common usage (e.g., blasting, some hazardous chemical uses). Strict liability applies to harm resulting from the kind of risk that makes the activity abnormally dangerous.

The central exam skill is to (1) identify the governing theory (strict liability vs negligence vs warranty) and (2) match the correct defense and its effect (complete bar vs reduction of damages vs no effect).

Defenses Applicable to Both Strict Liability and Products Liability

Certain defenses apply broadly across strict liability actions, including those for abnormally dangerous activities, animals, and defective products.

Comparative Fault / Contributory Negligence

The effect of the plaintiff's negligence varies by jurisdiction and by the type of claim.

Key Term: Comparative Fault
A defense asserting that the plaintiff's own negligence contributed to their injuries, which results in a proportional reduction of the plaintiff's recoverable damages based on their percentage of fault.

Key Term: Contributory Negligence
A defense (largely abolished) asserting that the plaintiff's own negligence, however slight, completely bars recovery if it contributed to their injuries.

1. Comparative Fault Jurisdictions (Majority)

Most states apply comparative fault principles to strict liability actions, including strict products liability. The plaintiff's own negligence (for example, using a product carelessly but in a foreseeable way) reduces their recovery in proportion to their degree of fault.

However, there is an important exam detail:

• Mere failure to discover a defect or to guard against the possibility of a defect is generally not treated as comparative fault in strict products liability. The whole point of strict liability is to shift the burden of discovering defects from consumers to manufacturers and sellers.
• By contrast, active and unreasonable conduct by the plaintiff (e.g., ignoring a clear warning, using the product in a clearly dangerous manner) may be treated as comparative fault and reduce recovery.

In negligence-based products liability (e.g., negligent design), ordinary comparative negligence rules apply: any unreasonable failure by the plaintiff to exercise reasonable care for their own safety can reduce their recovery.

2. Contributory Negligence Jurisdictions (Minority)

In the few jurisdictions still applying traditional contributory negligence, the plaintiff's unreasonable conduct might completely bar recovery—but with a significant limitation in strict liability cases:

• Simple negligent failure to discover or guard against a defect is typically not a defense in strict liability.
• Only conduct that effectively amounts to voluntarily and unreasonably encountering a known risk (similar to assumption of risk) will bar recovery.

In other words, in strict products liability and strict liability for abnormally dangerous activities, contributory negligence generally does not bar recovery unless it essentially overlaps with assumption of risk.

Also remember:

• Comparative or contributory negligence is not a defense to intentional torts, and that remains true even when the products liability claim is pled alongside intentional tort claims.

Assumption of Risk

If the plaintiff (1) knew of the specific risk associated with the abnormally dangerous activity or the defective product and (2) voluntarily chose to encounter it anyway, this constitutes assumption of the risk.

Key Term: Assumption of Risk
A defense alleging the plaintiff voluntarily proceeded to encounter a known, specific danger, which may bar or reduce recovery.

Assumption of risk is conceptually distinct from comparative fault: the emphasis is on knowledge and voluntary choice rather than on whether the plaintiff acted reasonably.

• The plaintiff must have actual subjective knowledge of the particular risk.
• The plaintiff must then voluntarily and unreasonably proceed in the face of that risk.

Types of Assumption of Risk

• Express Assumption of Risk
  This can occur via a written waiver or disclaimer (for example, signing a release before bungee jumping). Courts scrutinize such clauses and often refuse to enforce them if:

  • They attempt to disclaim liability for reckless or intentional conduct.
  • They involve essential services (e.g., medical treatment).
  • They violate public policy.

  In products liability tort actions seeking personal injury damages, contractual waivers are usually ineffective to bar strict liability claims, but they may still be effective for contract-based warranty claims (discussed later).

• Implied Assumption of Risk
  This is inferred from the plaintiff's conduct. The plaintiff must:

  • Actually know of the specific danger; and
  • Voluntarily choose to encounter it.

  Example: Continuing to use a product despite knowing it is defective and dangerous, without any necessity or compulsion.

Effect of Assumption of Risk

• In contributory negligence jurisdictions, assumption of risk is generally a complete bar to recovery.
• In some comparative fault jurisdictions, implied assumption of risk has merged into the comparative fault analysis and merely reduces damages.
• On the MBE, if the question highlights the plaintiff’s clear knowledge of a particular risk and a truly voluntary decision to confront it, assumption of risk is usually the strongest defense.

Key Term: Government Compliance
A defense argument that a product or activity complied with applicable governmental safety standards or regulations, offered as evidence that the product is not defective or that the defendant acted reasonably.

Key Term: Preemption
A defense asserting that federal law displaces or bars state tort claims, either because Congress expressly said so or because federal regulation occupies the field or conflicts with state law.

Key Term: Substantial Alteration
A significant, post-sale change to a product by the user or a third party that was not reasonably foreseeable to the manufacturer, and that causes the plaintiff’s injury.

Worked Example 1.1

Dynamite Corp. conducts blasting operations near a residential area. Homeowner is aware that Dynamite Corp. occasionally sends rocks flying onto nearby properties during blasts, as signs are posted warning of this danger. Despite this knowledge, Homeowner decides to sunbathe in his backyard during a scheduled blast. A rock lands nearby, startling Homeowner, who jumps up and sprains his ankle. Homeowner sues Dynamite Corp. under strict liability for abnormally dangerous activities. What is Dynamite Corp.'s strongest defense?

Answer:
Assumption of the risk. Homeowner knew of the specific risk (flying rocks during blasting) and voluntarily chose to encounter it by sunbathing during a scheduled blast. This knowing and voluntary encountering of the risk likely constitutes assumption of the risk, which would bar or significantly limit recovery. Comparative or contributory negligence might also be argued, but assumption of the risk, focusing on the knowing and voluntary encounter with the specific danger, is generally the stronger defense in a strict liability context.

Worked Example 1.2

In a comparative fault jurisdiction, Manufacturer sells a space heater. The product has no guard over the heating element (a design defect). Buyer places the heater very close to a stack of newspapers despite a general warning to “keep away from flammable materials,” and a fire ensues. Buyer sues Manufacturer in strict products liability for design defect. The jury finds Manufacturer 70% at fault and Buyer 30% at fault.

Answer:
Comparative fault applies. Manufacturer is strictly liable for selling a defective product, but Buyer’s decision to place the heater directly against flammable papers is negligent and contributed to the harm. The plaintiff’s damages will be reduced by 30%, reflecting Buyer’s comparative fault. The mere failure to inspect for hidden defects would not count as comparative fault, but active misuse of the product in an obviously unsafe way does.

Defenses Specific to Products Liability

In addition to comparative fault and assumption of risk, several defenses are particularly relevant in the context of products liability claims (whether based on strict liability, negligence, or warranty).

Key Term: Product Misuse
Use of a product in a manner neither intended nor reasonably foreseeable by the manufacturer or seller, which may serve as a defense to a products liability claim.

Key Term: Adequate Warning
A warning that sufficiently informs users of non-obvious risks associated with a product and instructs on safe use, potentially negating a claim of defect.

Key Term: State-of-the-Art Defense
A defense asserting that a product conformed to the level of scientific and technical knowledge existing at the time of manufacture or sale, often relevant in design defect and failure-to-warn cases.

Product Misuse

A manufacturer or seller is generally liable only if the product was defective when used in an intended or reasonably foreseeable manner. If the plaintiff uses the product in a way that is neither intended nor reasonably foreseeable, this constitutes product misuse.

Foreseeable Misuse

Manufacturers must take into account reasonably foreseeable but imperfect uses of products. Examples:

• Standing on a chair to reach a high shelf.
• Using a screwdriver as a pry bar.
• Driving a car a bit above the speed limit.

If such misuse is foreseeable:

• The manufacturer must design the product to be reasonably safe in light of that foreseeable misuse or provide adequate warnings.
• Foreseeable misuse is generally not a complete defense; instead, it may go to comparative fault (reducing recovery).

Unforeseeable Misuse

If the misuse is truly outside what a reasonable manufacturer should anticipate, it can be a complete defense:

• Using a ceiling fan as an airplane propeller.
• Disabling all safety devices on an industrial press in a way no reasonable manufacturer would anticipate or design around.
• Pouring gasoline into an electric appliance as a “cleaner.”

Exam angle: The more bizarre and idiosyncratic the misuse, the more likely it is unforeseeable and a complete defense.

Adequate Warning and Failure-to-Warn Claims

In claims based on design defects or failure-to-warn defects (both negligence and strict liability), the presence of an adequate warning or instruction can be a powerful defense. A product with built-in risks can be deemed non-defective if accompanied by adequate warnings and instructions.

The defendant will argue either:

• The warning given was adequate, so there is no defect; or
• The risk was obvious, so no warning was required.

When Is a Warning Adequate

Courts consider:

• Content: Does the warning clearly identify the specific risk and its gravity?
• Clarity: Is it understandable to the ordinary user (not buried in technical jargon)?
• Prominence: Is it conspicuous (placement, size, color)?
• Specificity: Vague warnings (“use safely”) are less effective than specific ones (“keep at least three feet from flammable materials”).

Some jurisdictions apply a heeding presumption: if an adequate warning had been given, it is presumed the plaintiff would have read and heeded it. The defendant can rebut this by showing the particular plaintiff would have ignored the warning anyway.

Obvious Dangers

Manufacturers have no duty to warn of risks that are obvious to the ordinary user:

• A knife is sharp.
• A stove gets hot when turned on.

But do not overextend this on the exam: even with obvious dangers, warnings may be needed if:

• There are non-obvious aspects of the risk (e.g., a particular power tool can kick back in an unusual way).
• The product is marketed to especially vulnerable users (children).

Learned Intermediary Rule (Prescription Drugs)

Key Term: Learned Intermediary Rule
A doctrine under which a prescription drug manufacturer satisfies its duty to warn by adequately warning the prescribing physician, who then acts as a “learned intermediary” between manufacturer and patient. An exception often exists where drugs are marketed directly to consumers.

For prescription drugs and certain medical devices:

• The manufacturer’s duty is to warn the prescribing physician, not the patient directly.
• If the manufacturer gives the doctor an adequate warning, and the doctor fails to convey that information, the manufacturer is generally not strictly liable for failure to warn.

Exception commonly tested: where a drug is heavily marketed directly to consumers, some jurisdictions require adequate warnings to patients as well.

Worked Example 1.3

A consumer buys a powerful drain cleaner. The label prominently displays in large red letters: "DANGER! CORROSIVE! Wear gloves and eye protection. Do NOT mix with other chemicals." The consumer, ignoring the warning, mixes the cleaner with bleach, causing a chemical reaction that releases toxic fumes and injures the consumer. The consumer sues the manufacturer under strict products liability, claiming the product was defective due to inadequate warning about the specific risk of mixing with bleach. Will the manufacturer likely prevail?

Answer:
Yes. The manufacturer provided a clear, prominent warning against mixing the product with other chemicals, which adequately addressed the type of misuse that caused the injury. Assuming the warning reasonably conveyed the seriousness of the danger, it is likely deemed adequate, negating a failure-to-warn defect. The consumer’s decision to ignore the warning may also constitute comparative fault or implied assumption of risk, further reducing or barring recovery.

Substantial Alteration and Modification

Key Term: Substantial Alteration
A significant, unforeseeable change to a product after it leaves the manufacturer’s control that creates or magnifies a risk and causes the plaintiff’s injury.

If a product is substantially altered by the plaintiff or a third party after leaving the manufacturer's or seller's control, and this alteration causes the injury:

• The manufacturer is generally not liable, provided the alteration was not reasonably foreseeable.

Examples:

• Removing a saw’s blade guard in a non-obvious, non-anticipated way.
• Rewiring an appliance contrary to instructions.
• Retrofitting industrial machinery with homemade parts that change safety characteristics.

If modifications are foreseeable, manufacturers may be required to design around them or provide warnings (e.g., foreseeable removal of a simple guard); failure to do so may mean this “modification” does not constitute a complete defense.

Component-part manufacturers can also raise this defense if:

• The component itself was not defective when sold; and
• The way the finished product maker integrated the component (or altered it) caused the danger.

State-of-the-Art Defense

This defense is most relevant in design defect and failure-to-warn cases. It asserts that the product conformed to the level of scientific and technical knowledge existing at the time the product was manufactured or sold.

• In some jurisdictions, state-of-the-art compliance is only evidence that the design was not defective or that warnings were adequate.
• In others, particularly for strict design defect claims, it can be a complete defense (the manufacturer could not have known or avoided the risk with existing technology).

State-of-the-art is especially important with:

• Pharmaceuticals and medical devices.
• Emerging technologies (e.g., early-generation products where risks were not yet scientifically recognized).

On the MBE, if the fact pattern emphasizes that a risk was scientifically unknowable at the time—even with reasonable testing—state-of-the-art is likely the key defense.

Government Compliance and Preemption

Key Term: Government Compliance
Compliance with applicable governmental safety regulations, offered as evidence that a product is not defective or that the defendant used reasonable care.

Key Term: Preemption
A doctrine under which valid federal law displaces conflicting state law, including state tort claims, either because Congress expressly said so or because federal regulation occupies the field or creates a conflict.

Compliance

• Mere compliance with safety regulations (e.g., meeting OSHA or FDA standards) is relevant evidence that a product is not defective, but it is usually not conclusive.
• Non-compliance, by contrast, is strong evidence of a defect or negligence.

Exam tip: Do not automatically treat compliance as an absolute defense unless the question expressly states that the jurisdiction treats compliance as conclusive.

Federal Preemption

In limited situations, federal law preempts state tort claims:

• Some heavily regulated areas (for example, certain Class III medical devices with premarket approval).
• Certain prescription drug labeling contexts, particularly where federal regulations leave no room for unilateral strengthening of warnings by the manufacturer.

If preemption applies:

• The state tort claim is barred entirely, regardless of defectiveness or plaintiff conduct.

On an MBE-style question, preemption is usually signaled by explicit reference to a federal statute or regulation that:

• Contains an express preemption clause; or
• Occupies the entire field of regulation, and the fact pattern contrasts state tort duties with federal requirements.

Contractual Defenses (Warranty Claims)

While disclaimers and limitations of remedy are generally ineffective in strict products liability tort actions involving personal injury, they can be effective in claims based on breach of warranty (a contract-based theory), especially concerning economic loss.

• Disclaimers of Implied Warranties
  Under the UCC, a seller may disclaim implied warranties (merchantability, fitness) if:

  • The disclaimer is conspicuous; and
  • For merchantability, it mentions “merchantability”; and
  • For fitness, it is in a signed writing.

• Limitations of Remedy
  Contract language may limit the buyer’s remedies (for example, “repair or replacement only”). Such limitations are generally enforceable for economic loss, unless unconscionable.

• Notice of Breach
  Under the UCC, a buyer must notify the seller of a breach of warranty within a reasonable time after discovering it, or be barred from any remedy.

These contractual rules do not bar a strict products liability tort claim for personal injuries, but can:

• Defeat warranty claims that accompany the strict liability count.
• Limit recovery for purely economic loss to contract remedies.

Worked Example 1.4

Buyer purchases a new lawnmower from Retailer. The sales contract conspicuously states, “Seller disclaims all implied warranties. Seller’s liability is limited to repair or replacement of defective parts.” The mower’s blade detaches due to a hidden manufacturing defect and severely injures Buyer’s foot. Buyer sues Retailer in (1) strict products liability in tort and (2) breach of implied warranty of merchantability.

Answer:
The disclaimer and remedy limitation may defeat or limit the warranty claim, provided they satisfy UCC requirements and are not unconscionable. However, they do not bar the strict products liability tort claim for personal injury. Retailer can still be strictly liable in tort for distributing a defective product that caused bodily harm, regardless of contractual disclaimers.

Exam Warning

Do not confuse defenses applicable to negligence (like contributory or comparative negligence) with those applicable to strict liability. While comparative fault is now applied to strict liability in most jurisdictions, the historical distinction and the differing applications (for example, simple failure to discover a defect usually not being fault in strict products liability) are important for the MBE.

Also:

• Traditional contract defenses like disclaimers are far less effective against strict liability tort claims than against warranty claims.
• In strict liability for abnormally dangerous activities and animals, contributory negligence is usually irrelevant unless it amounts to assumption of risk.
• Always ask: What is the governing theory? Negligence, strict liability, or warranty. The availability and effect of defenses differ by theory.

Summary

Defenses in strict liability and products liability cases focus on:

• The plaintiff's conduct (comparative fault, assumption of risk, unforeseeable misuse).
• The nature of the product and the accompanying information (adequate warnings, state-of-the-art, substantial alteration).
• External legal frameworks (government compliance, federal preemption).
• Contractual allocation of risk (disclaimers and remedy limitations) in warranty actions.

Key points:

• Comparative fault (majority rule) typically reduces the plaintiff's recovery in strict liability, including strict products liability, based on the plaintiff’s percentage of fault. Simple failure to detect a defect is usually not fault.
• Contributory negligence (minority rule) generally does not bar recovery in strict liability unless the plaintiff’s conduct amounts to assumption of risk.
• Assumption of risk (knowing, voluntary encounter with a specific risk) is often a complete defense, especially in contributory negligence jurisdictions and in strict liability for abnormally dangerous activities.
• Unforeseeable product misuse and substantial, unforeseeable alteration of a product after it leaves the defendant's control can defeat liability entirely; foreseeable misuse typically feeds into comparative fault rather than complete exoneration.
• An adequate warning of non-obvious risks can render a product non-defective; the learned intermediary rule is central in prescription drug cases.
• The state-of-the-art defense argues conformity with available scientific knowledge and technology at the time of manufacture or sale; in some jurisdictions, it is only evidence, in others a complete defense.
• Compliance with government safety standards is evidence of non-defectiveness but usually not conclusive. Federal preemption can completely bar state tort claims in limited, heavily regulated contexts.
• Disclaimers and remedy limitations are generally ineffective against strict tort liability for personal injury but may be valid and important in warranty claims, especially for economic loss.

Key Point Checklist

This article has covered the following key knowledge points:

• Comparative fault (majority rule) reduces plaintiff's recovery in strict liability and strict products liability based on the plaintiff’s percentage of fault, but mere failure to discover a defect is typically not fault.
• Contributory negligence (minority rule) generally does not bar strict liability recovery unless plaintiff's conduct effectively amounts to assumption of risk.
• Assumption of risk (knowing, voluntary encounter with a specific risk) is often a complete defense, especially in strict liability for abnormally dangerous activities and animals.
• Unforeseeable product misuse and substantial, unforeseeable alteration of a product are defenses; foreseeable misuse generally is not a complete defense (though it may support comparative fault).
• An adequate warning of non-obvious risks can render a product non-defective; obvious dangers often require no warning.
• The learned intermediary rule focuses the duty to warn on the prescribing physician in prescription drug cases, with exceptions for direct-to-consumer marketing.
• Substantial, unforeseeable alteration of a product after it leaves the defendant's control is a defense; foreseeable modifications may need to be designed against or warned about.
• The state-of-the-art defense argues conformity with available technology and scientific knowledge at the time of manufacture or warning.
• Compliance with government safety standards is evidence of non-defectiveness but usually not conclusive; non-compliance is strong evidence of defect.
• Federal preemption can sometimes bar state tort claims regarding product safety or warnings in areas of pervasive federal regulation.
• Disclaimers and remedy limitations are generally ineffective against strict tort liability for personal injury but may be valid and important in warranty claims, especially for economic loss.
• Comparative fault and assumption of risk are treated differently across negligence, strict liability, and warranty theories; always identify the governing theory before selecting a defense.

Key Terms and Concepts

• Comparative Fault
• Contributory Negligence
• Assumption of Risk
• Product Misuse
• Adequate Warning
• State-of-the-Art Defense
• Substantial Alteration
• Government Compliance
• Preemption
• Strict Products Liability
• Abnormally Dangerous Activity
• Learned Intermediary Rule