How to Prove a Products Liability Claim

Understand how to get compensated for your defective product injuries

By Canaan Suitt, J.D. | Last updated on May 2, 2023 Featuring practical insights from contributing attorney Michael J. Epstein

Use these links to jump to different sections:

Defectively built or dangerous products 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 attorney in your area 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 products liability lawsuit: 


First, you must show that a product injured you. If you just 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 normal pressure to chop. You’re chopping vegetables, and the blade flies off, nearly stabbing your foot. You’re able to move out of the way and not get injured.

Even though the knife was defectively built and almost caused you serious injury, you weren’t harmed and won’t have a good claim. 


Next, you must show the product that caused your injuries was defective.

Many non-defective products can injure you—for example, if they’re handled incorrectly. You must show that the reason the product harmed you was that it was defective.


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, 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 usual way when you got injured and not trying to juggle with it 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.

Michael J. Epstein

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 (defective manufacture, defective design, 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 

Many product liability cases involve strict liability. The supplier of the product is responsible for injuries resulting from defects, even if they were extremely careful in making the product.  

In a strict liability case, the injured party simply has to show 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.”


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 are explicitly written or orally stated. They often appear on labels and instructions for products.  
  • Implied 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 

This is a Latin term that means “the thing speaks for itself.”  

In the context of 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) usually 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 this list of different legal theories shows, product liability can be 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? 

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,” says Epstein, “you have to be a user.” 

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

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 in the future. 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

Individuals 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.  

Questions for a Products Liability Attorney 

If you are considering a product liability lawsuit, consider speaking with an experienced personal injury lawyer about your case. 

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. 

To get the most out of a consultation, ask informed questions such as: 

  • What are your attorney’s fees? 
  • How is product liability determined under my state’s laws? 
  • What is the statute of limitations for filing a lawsuit? 
  • How likely is a settlement before going to trial? 

Once you have met with a product liability lawyer and gotten your questions answered, you can begin an attorney-client relationship. 

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.

Find top lawyers with confidence

The Super Lawyers patented selection process is peer influenced and research driven, selecting the top 5% of attorneys to the Super Lawyers lists each year. We know lawyers and make it easy to connect with them.

Find a lawyer near you