Liability is usually available for abnormally dangerous activities and for defective products.

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To this point, we have considered principles of liability that in some sense depend upon the “fault” of the tortfeasor. This fault is not synonymous with moral blame.

Aside from acts intended to harm, the fault lies in a failure to live up to a standard of reasonableness or due care. But this is not the only basis for tort liability. Innocent mistakes can be a sufficient basis. As we have already seen, someone who unknowingly trespasses on another’s property is liable for the damage that he does, even if he has a reasonable belief that the land is his. And it has long been held that someone who engages in ultrahazardous (or sometimes, abnormally dangerous) activities is liable for damage that he causes, even though he has taken every possible precaution to avoid harm to someone else.

Likewise, the owner of animals that escape from their pastures or homes and damage neighboring property may be liable, even if the reason for their escape was beyond the power of the owner to stop (e.g., a fire started by lightning that burns open a barn door). In such cases, the courts invoke the principle of strict liability, or, as it is sometimes called, liability without fault. The reason for the rule is explained in Klein v. Pyrodyne Corporation (Section 7.5 "Cases").

Products liability is extremely important. Strict liability may also apply as a legal standard for products, even those that are not ultrahazardous. In some national legal systems, strict liability is not available as a cause of action to plaintiffs seeking to recover a judgment of products liability against a manufacturer, wholesaler, distributor, or retailer. (Some states limit liability to the manufacturer.) But it is available in the United States and initially was created by a California Supreme Court decision in the 1962 case of Greenman v. Yuba Power Products, Inc.

In Greenman, the plaintiff had used a home power saw and bench, the Shopsmith, designed and manufactured by the defendant. He was experienced in using power tools and was injured while using the approved lathe attachment to the Shopsmith to fashion a wooden chalice. The case was decided on the premise that Greenman had done nothing wrong in using the machine but that the machine had a defect that was “latent” (not easily discoverable by the consumer). Rather than decide the case based on warranties, or requiring that Greenman prove how the defendant had been negligent, Justice Traynor found for the plaintiff based on the overall social utility of strict liability in cases of defective products. According to his decision, the purpose of such liability is to ensure that the “cost of injuries resulting from defective products is borne by the manufacturers…rather than by the injured persons who are powerless to protect themselves.”

Today, the majority of US states recognize strict liability for defective products, although some states limit strict liability actions to damages for personal injuries rather than property damage. Injured plaintiffs have to prove the product caused the harm but do not have to prove exactly how the manufacturer was careless. Purchasers of the product, as well as injured guests, bystanders, and others with no direct relationship with the product, may sue for damages caused by the product.

The Restatement of the Law of Torts, Section 402(a), was originally issued in 1964. It is a widely accepted statement of the liabilities of sellers of goods for defective products. The Restatement specifies six requirements, all of which must be met for a plaintiff to recover using strict liability for a product that the plaintiff claims is defective:

  1. The product must be in a defective condition when the defendant sells it.
  2. The defendant must normally be engaged in the business of selling or otherwise distributing the product.
  3. The product must be unreasonably dangerous to the user or consumer because of its defective condition.
  4. The plaintiff must incur physical harm to self or to property by using or consuming the product.
  5. The defective condition must be the proximate cause of the injury or damage.
  6. The goods must not have been substantially changed from the time the product was sold to the time the injury was sustained.

Section 402(a) also explicitly makes clear that a defendant can be held liable even though the defendant has exercised “all possible care.” Thus in a strict liability case, the plaintiff does not need to show “fault” (or negligence).

For defendants, who can include manufacturers, distributors, processors, assemblers, packagers, bottlers, retailers, and wholesalers, there are a number of defenses that are available, including assumption of risk, product misuse and comparative negligence, commonly known dangers, and the knowledgeable-user defense. We have already seen assumption of risk and comparative negligence in terms of negligence actions; the application of these is similar in products-liability actions.

Under product misuse, a plaintiff who uses a product in an unexpected and unusual way will not recover for injuries caused by such misuse. For example, suppose that someone uses a rotary lawn mower to trim a hedge and that after twenty minutes of such use loses control because of its weight and suffers serious cuts to his abdomen after dropping it. Here, there would be a defense of product misuse, as well as contributory negligence. Consider the urban (or Internet) legend of Mervin Gratz, who supposedly put his Winnebago on autopilot to go back and make coffee in the kitchen, then recovered millions after his Winnebago turned over and he suffered serious injuries. There are multiple defenses to this alleged action; these would include the defenses of contributory negligence, comparative negligence, and product misuse. (There was never any such case, and certainly no such recovery; it is not known who started this legend, or why.)

Another defense against strict liability as a cause of action is the knowledgeable user defense. If the parents of obese teenagers bring a lawsuit against McDonald’s, claiming that its fast-food products are defective and that McDonald’s should have warned customers of the adverse health effects of eating its products, a defense based on the knowledgeable user is available. In one case, the court found that the high levels of cholesterol, fat, salt, and sugar in McDonald’s food is well known to users. The court stated, “If consumers know (or reasonably should know) the potential ill health effects of eating at McDonald’s, they cannot blame McDonald’s if they, nonetheless, choose to satiate their appetite with a surfeit of supersized McDonald’s products.”

Common-law courts have long held that certain activities are inherently dangerous and that those who cause damage to others by engaging in those activities will be held strictly liable. More recently, courts in the United States have applied strict liability to defective products. Strict liability, however, is not absolute liability, as there are many defenses available to defendants in lawsuits based on strict liability, such as comparative negligence and product abuse.


  1. Someone says, “Strict liability means that you’re liable for whatever you make, no matter what the consumer does with your product. It’s a crazy system.” Respond to and refute this statement.
  2. What is the essential difference between strict liability torts and negligent torts? Should the US legal system even allow strict liability torts? What reasons seem persuasive to you?

Strict liability and products liability are foundational theories of legal liability relied on by personal injury lawyers when seeking justice for clients who have suffered at the hands of third parties. These two theories are related and share similarities—but they are not identical.

Strict Liability: Liability No Matter the Level of Fault

In contrast to intentional torts and negligence, the legal theory of strict liability does not rely on the intent of a defendant or how their actions compare to what a reasonable person might have done. Instead, strict liability is imposed on a defendant solely based on the nature of their alleged conduct.

There are three kinds of conduct that give rise to strict liability. The first is the possession of animals known to be harmful. For example, if a property owner keeps on their property, an aggressive dog that has previously attacked, and it attacks a visitor, the property owner could be strictly liable for the visitor’s injuries regardless of the precautions taken to prevent an attack.

The second type of conduct that gives rise to strict liability is engaging in abnormally dangerous activities. Typically, an abnormally dangerous activity (1) is not commonly undertaken in a community or under certain circumstances, (2) creates foreseeable and significant potential harm to people or property and (3) carries with it a high degree of risk of harm that cannot be abated through the exercise of reasonable care. Examples of abnormally dangerous activities might include storing hazardous waste in a residential area and using dynamite near a densely populated part of town.

Products Liability: A Unique Form of Strict Liability

The third kind of conduct that gives rise to strict liability is products liability. Products liability is the theory of legal liability under which the manufacturer or seller of a defective product is held liable for injuries to a consumer caused by that product’s use. In a products liability case, any or all parties that are involved in a product’s chain of distribution—including the manufacturer, distributor and the retailer that sold the product to the consumer—can be liable for a consumer’s injuries.

There is no federal products liability law. Therefore, the laws of products liability vary from state to state. Although the United States Department of Commerce published the Model Uniform Products Liability Act (MUPLA) in 1979 to create uniform U.S. products liability law, it has not been widely adopted. The American Law Institute’s Restatement (Third) of Torts: Products Liability, for example, does not cite often to the MUPLA.

In most states, products liability claims are based on the theory of strict liability. In states where strict liability is not the theory of liability, the theory falls to negligence, or breach of warranty of fitness.

In states where strict liability is the theory of liability, manufacturers and sellers are generally liable for injuries to people caused by the goods they manufacture or sell regardless of their intent or the amount of reasonable care they exercise. To prevail in a strict liability products liability case, a plaintiff must show by the preponderance of the evidence that:

  1. They suffered physical harm to themself or their property after using or consuming the product.
  2.  The product was defective when sold by the defendant.
  3.  The defendant customarily engages in the business of distributing or selling the product.
  4.  The product’s defective condition rendered it unreasonably dangerous to the plaintiff.
  5.  The product’s defective condition was the proximate cause of the plaintiff’s injuries.
  6.  The product was not substantially changed between the time the defendant distributed or sold the product and the time the injury occurred.

A product is “unreasonably dangerous” to a consumer’s health and safety if it is dangerous beyond an ordinary consumer’s expectation or the manufacturer did not produce a less dangerous alternative that was economically feasible. Product defects can injure consumers in countless ways, but there are only three types of defects commonly recognized as giving rise to a products liability claim:

  1. Design defects, which arise when a product was designed in a flawed manner.
  2.  Manufacturing defects, which arise when there was a problem with the production of a product.
  3.  Marketing defects, which arise when a product is accompanied by instructions that are incorrect, false or fail to warn consumers of the product’s dangers.

Common Defenses to Strict Liability & Products Liability Claims

Because strict liability claims and products liability claims in strict liability jurisdictions do not rest on the intent of the defendant, intent-based defenses will be of no help. But that does not mean they are without potent defenses. In strict liability and products liability cases, defendants may be able to prevail on defenses such as:

  1. Assumption of risk, where the plaintiff knew about the risk created by the dangerous condition or product, and voluntarily assumed the risk of interacting with it, even if it was unreasonable to do so.
  2. Product misuse, where the plaintiff used a product in a way or for a purpose other than that for which it was designed, and the misuse was not foreseen by the defendant.
  3. Commonly known danger, where the plaintiff’s injury resulted from a danger that is commonly known by the public.
  4. Knowledgeable user, where the dangerous condition or product is or should be commonly known by users.
  5. Federal preemption, where a defendant who complies with federal laws and regulations when manufacturing its product cannot be liable under state products liability law that conflicts or interferes with those federal mandates.
  6. Expiration of the statute of limitations.
  7. Expiration of the statute of repose.

Additionally, a defendant in a products liability case that faces allegations of a design defect in their product may have additional defenses at their disposal through the application of two tests:

  1. Risk-utility test, where a defendant will not be liable for a design defect if there is evidence that the product’s utility when using it as designed outweighs its risk of harm; or
  2. Consumer expectation test, where a reasonable consumer would not find the product to be defective when used in a reasonably foreseeable manner.

As discussed, strict liability and products liability are indeed distinct legal theories—with plenty of overlap. Volumes of legal precedent exists in this area and understanding the interplay between the two theories should bring clarity to personal injury lawyers considering which to assert in a client matter.