How To Prove a Product Liability Claim
By Canaan Suitt, J.D. | Last updated on May 21, 2025 Featuring practical insights from contributing attorney Michael J. EpsteinDefectively built or dangerous product can result in serious injuries, leading to medical expenses and time away from work. If a defective or dangerous product has injured you, a product liability lawsuit can allow you to recover damages resulting from your injuries.
This article will give an overview of the different types of product liability claims and how these claims are generally proven. Once you have overviewed this area of law, it’s a good idea to speak with an experienced product liability lawyer about your situation.
“It’s better to reach out to a lawyer sooner rather than later, so the lawyer can protect and preserve [your] rights,” says New Jersey personal injury lawyer Michael J. Epstein.
What Are the Elements of a Product Liability Claim?
Although product liability laws vary by jurisdiction, there are usually four things you must prove in order to win any product liability lawsuit:
Injury
First, you must show that a product injured you. If you had a close call with a defective product but weren’t actually harmed, you won’t have a successful claim.
For example, say you’re using a new knife that was defectively manufactured so that the blade detaches from the handle when you apply pressure. You’re chopping vegetables, and the blade flies off, nearly injuring your foot. You’re able to move out of the way and not get injured. Even though the knife was defectively built and nearly injured you, you weren’t harmed and won’t have a good claim.
Defectiveness
Next, you must show that the product’s defect is what injured you, not some other reason such as user error. After all, many products can injure you if you handle them incorrectly. You must show that the reason the product harmed you was that it was defective.
Causation
Next, you have to show that the product’s defect was the proximate cause of your injuries. This simply means that the defective product, and not some other factor at the same time, caused your injuries.
Proper Use
Finally, you must show that you were using the product as intended when it injured you. Returning to the defective knife example, you would have to show that you were chopping vegetables in a normal way when you got injured — not trying to juggle with the knife or some other improper use.
What Are the Types of Product Defect Claims?
“In general, there are three claims for product liability: Manufacturing claims, design defect claims, and where there’s a known risk, failure to warn claims,” says Epstein.
- Manufacturing defect. This is when the defect in the product was caused by the product being incorrectly built or manufactured. The design was correct, but the execution was flawed. Manufacturing defects tend to happen at the beginning of the distribution chain, at the factory or business where the product was made.
- Design defect. This is when the product was correctly manufactured according to the product design, but there was some error in the design itself. Proving a defective product design can be more difficult than proving a manufacturing defect. You have to show how the product’s design caused the defect that resulted in your injuries.
- Failure to warn. This type of case arises when the manufacturer or retailer provides inadequate warnings about a dangerous product. The product isn’t defectively built or designed, but it is dangerous in a way that the ordinary consumer would not have known without proper labeling or some other type of warning.
There are [generally] three claims for product liability: Manufacturing claims, design defect claims, and where there’s a known risk, failure to warn claims.
Who Is Responsible for Product Defects?
Many different parties along the chain of distribution could be liable for product defects. The party responsible will depend partly on the type of claim you bring, such as defective manufacture, defective design, or inadequate warning. Some of the most common responsible parties include:
- The product manufacturer
- Component parts manufacturers
- Wholesalers of the product
- Retail stores that sell the product
Theories of Liability
There are several legal theories of liability in product defect cases.
Strict Liability
Under strict liability, the product supplier is responsible for injuries resulting from defects even if they were extremely careful in making the product. The injured party doesn’t have to prove intent or negligence, just that the product was defective and they were injured by it.
Strict liability for defective products is imposed by state laws. “If a plaintiff proves a product liability claim, then under the product liability statute in New Jersey, there’s strict liability,” says Epstein. “In most personal injury cases, you’re assessing whether there’s negligence — whether a reasonably prudent person would have committed or failed to do the act. But in strict liability, negligence doesn’t come into play.”
Negligence
Proving negligence isn’t part of a strict liability claim. But depending on your state and case, some product liability lawsuits may rest on a theory of negligence instead of strict liability.
According to a negligence claim, the supplier had a duty to act with reasonable care in manufacturing, designing, or distributing the product. The supplier failed to exercise reasonable care and that caused the injured person actual harm.
Breach of Warranty
Breach of warranty claims arise when you have a warranty on the product that guarantees the product’s condition, and the product defect violates the warranty. There are two general types of warranties:
- Express warranties. These warranties are explicitly written or orally stated. They often appear on labels and instructions for products.
- Implied warranties. These warranties are legally assumed to apply to the product. For example, state laws assume that products have an implied warranty of merchantability. This means the product is fit to be sold and isn’t broken, spoiled, or otherwise defective.
Res Ipsa Loquitur
Res ipsa loquitur is a Latin phrase that means “the thing speaks for itself.” In product liability law, res ipsa loquitur means a defect in the product would not have existed unless someone was negligent in making it. The defective product “speaks for itself” to the fact that someone was negligent somewhere along the line.
When this theory comes into play in a lawsuit, the burden of proof shifts from the plaintiff to the defendant. In other words, the person harmed (plaintiff) normally has to prove there was a defect that caused their injuries. The burden of proof is on them. But under res ipsa loquitur, the person or company being sued (defendant) must prove that they were not negligent. The burden of proof is on them.
Making Sense of Your Product Liability Claim
As the above list of legal theories shows, product liability can become very complicated. What sort of claim should you bring if a defective product has injured you? How do you get started with proving your case?
Speaking with an experienced lawyer is essential. A lawyer will understand the law well and be able to help you formulate the best legal strategy.
Who Can Sue for Product Liability?
Traditionally, in order to bring a product liability lawsuit, you had to be the person who purchased the product directly from a retailer or supplier. This requirement was known as “privity of contract.”
In modern product liability law, this general requirement no longer holds. “You don’t necessarily have to be the purchaser of the product; you have to be a user,” says Epstein.
Anyone who would be foreseeably affected by the defective product can bring a product liability lawsuit against the supplier. For example, “Say there’s a person working in a factory and [there’s no guard on the machine they’re operating],” says Epstein. “The person’s hand gets stuck in the machine, resulting in lost fingers or a hand. In that situation, the worker was never going to purchase the factory machinery, but they have suffered injuries from a defective product and can sue.”
Statutes of Limitations in Product Liability Claims
Every state has a law called the statute of limitations that sets the deadline for filing a product liability lawsuit. In most states, the timeframe is between two and six years from when the injury occurred. Some states have longer timeframes, and a few have shorter ones.
Statutes of limitations are very important. If you miss the deadline, you can’t file a lawsuit. This means you will miss out on any compensation you might have gained through a lawsuit.
To ensure you don’t miss your state’s deadlines, consider speaking with a product liability lawyer in your area.
Preparing for a Lawsuit with an Attorney
People injured by a defective or dangerous product should take the following steps following an accident:
- Get medical treatment
- Report the accident
- Document the evidence
- Get a lawyer
To document evidence in a product liability case, injured persons “need to keep the product so it can be evaluated for defects. If the product is thrown away, lost, or altered, it can be hard to assess the case,” says Epstein.
Find a Product Liability Attorney
Many product liability attorneys provide free consultations to learn about your case. These consultations include legal advice and help decide if the attorney or law firm meets your needs.
Look for a product liability attorney in the Super Lawyers directory for help with your product liability case.
What do I do next?
Enter your location below to get connected with a qualified attorney today.Additional Products Liability articles
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- What To Do If Your Product Injured a Consumer
- How Long Do I Have To Sue For an Injury Caused by My Defective Product?
- What To Do if You’re Injured by a Defective Product
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