What Is Patent Infringement?

Patent infringement means that a person makes, sells, imports, or uses someone else's patented idea or invention. This is easy, since patents are public documents and all the information is readily available. But it is illegal. If the patent holder sues, the court could direct the defendant to stop the illegal activity. The patent holder could also receive monetary damages for the unauthorized use of the patent. Patented ideas or designs usually have many parts, so a patent infringement could result in several claims.

What Are the Stages of Patents?

The inventor makes an invention or comes up with an idea. At this stage, the inventor doesn't own the invention or idea or have any rights to it.

  1. The inventor documents the concept using a provisional patent.

  2. Once a provisional patent is granted, the patent is pending. The inventor now has some rights to the invention and could sue if someone else tries to use it. Patenting an invention is a lengthy process. The provisional patent allows for a one-year waiting period before the non-provisional patent is filed. It's common for a company to announce that a patent is pending to inform competitors. The U.S. Patent and Trademark Office (USPTO) may grant the final patent after several months. The inventor may ask that the USPTO not release the patent until he or she is ready to use it.

  3. The patent is enforceable once the USPTO issues the patent.

  4. Unless the patent is renewed, it eventually expires. Then the patent owner no longer has sole rights to the invention.

It's important to understand that owning a patent doesn't mean that someone else will enforce it for you. The USPTO only grants patents, but it does not enforce them. This is a matter for a court to decide.

Explaining Patent Claims

Before creating a patent claim, use your patent file as your primary resource. Make sure that your patent records show that the other party used your invention without your permission.

A patent claim states that someone else has infringed on your patent. The claim must show proof that someone used your patented idea or product. Even if the new item is different from or better than the original item, the claim could still be valid. 

Patent claims are different for processes versus methods. If the alleged infringer proves that he or she used a method more than a year before the patent was issued, he or she may not be guilty of patent infringement. 

Analyzing Patent Infringement

Key Terms for Patent Infringement

  • The infringer is the person or company who is responsible for patent infringement

  • A contributory infringer is someone who helps or offers to create or sell a patented invention

  • Multiple infringers refers to more than one person or company that infringes on the same patent

Claim Construction

It's important to understand the court's procedures when building a claim. First, the court determines if the infringement claim is relevant. Once the claim terms are created, the court decides if the claims apply to the patented item. 

The Federal Circuit offers suggestions for understanding claims:

  • The patent holder can use his or her own words as long as the meanings of those words are clear

  • Specifications should only offer support of the claim, not change the claim

  • Each claim should show that it's different from the other claims

  • When there are multiple interpretations, the one that keeps the claim valid is most important

Interpreting Claims

Phillips v. AWH Corp., 415 F.3d 1303 (Federal Circuit 2005) offers the approach of interpreting claims.

  • Begin with a claim. The writing should be easy to understand even if the patent or invention is technical. The claim should give guidance in understanding the meaning of the claim.

  • Consider the entire patent. It should be considered in its entirety even if parts are not relevant. The specification is the most important guide to the dispute. If the specification offers disclaimers or inaccuracies, it could mean the patent is invalid.

  • Make sure that someone with limited knowledge can understand the claim terms

  • Check the legal history of the patent, which presents information on earlier perceptions of the patent

  • Look at the evidence submitted by testimonies of the creator and expert witnesses from earlier legal cases

Make sure you realize that the inventor's concept of his patent does not mean that the inventor understands the claims. The inventor's intention is not always relevant to claim construction.

What Are the Types of Patent Infringement?

Direct Infringement

Someone creates the product without the patent holder's permission. The infringer doesn't have to know that the patent exists in order for the patent owner to sue him or her for direct infringement. That person can't make, use, offer, sell, or import a patented invention whether or not he or she know a patent exists. 

Indirect Infringement 

The infringer did not directly infringe on the patent, but may have encouraged or helped to infringe on the patent.

Induced Infringement

This refers to inducing or persuading someone to make a patented invention. This term is often used in the same way as indirect infringement. 

Contributory Infringement

Someone provides a part or a product to help someone else infringe a patent. That part or product must not have any other reasonable use. 

Literal Infringement

To prove literal infringement in court, all elements of a defendant's device or idea must be present in the patented one.  

Doctrine of Equivalents

The Doctrine of Equivalents refers to something that is created in such a way that it does the same thing, in the same way, producing the same result as the patented item. It is relevant even when the new product is better or different from the original. 

Festo Corp. v. Shoketsu Kinsoky Kabushiki Co., 535 U.S. 722 (2002) is a court case that changed the way courts view the Doctrine of Equivalents. This doctrine is only relevant if the patent holder can prove that amending his or her patent claims doesn't give up the equivalents. This case changed the standard in a way that is confusing even for experienced patent lawyers. 

KSY v. Teleflex, 550 U.S. (2007) changed the rules when it found that typical innovations can't be patented. 

Willful Infringement

Willful infringement means that another person or company purposely used someone else's patented ideas or products. A simple way to disprove willful infringement is to hire a patent attorney, who presumably will inform his or her client if infringement is about to occur. 

It's common for a court to award treble damages in cases of willful infringement, which can serve to prevent it due to their size. 

Understanding Patent Infringement Litigation

The patent owner is responsible for proving patent infringement. It's similar to the concept that a criminal suspect is innocent until proven guilty. The alleged infringer doesn't need to prove he or she is innocent. Expert witnesses are often used to help prove guilt.

Litigation must occur in federal court because patents are intellectual property. The patent holder must sue within six years from when the alleged infringement occurs. Most of the time, a judge decides the outcome of the case instead of a jury.

  • Question of Law means that the judge has the final say in the case, not a jury

  • Question of Fact means that the charges may be decided by either a judge or a jury

Patents are intellectual property. That means that in the United States, they are not a criminal matter. There is no police protection against patent infringement. You must sue someone in civil court for that person to be held accountable.

Patent Infringement Defenses

The most common defense to patent infringement is that the patent is not valid. A patent could be invalid for a variety of reasons:

  • The patent holder was dishonest on the application

  • The patent holder included wrong or misleading information on the patent

  • A person used the patented item or idea for illegal activity

  • The patent violates antitrust and other competition laws

  • It did not meet novelty and non-obvious requirements

To meet the novelty requirement, the product or idea has to be brand new. The non-obvious requirement means that the invention isn't just a modified version of a previous design.

Length of Patent Protection

Patent infringement only exists before the patent expires.

  • A utility patent expires after 20 years from the date filed or 17 years from its issue date. These numbers are only for patents filed before June 8, 1995.

  • After June 8, 1995, the patent lasts for 20 years from the filing date

  • Design patents expire 14 years after they are issued

  • Plant patents last 17 years after they are issued

Patents also expire if the patent holder does not pay maintenance fees. A patent holder might opt out of paying fees if the invention doesn't work. In that case, they probably don't care about the patent enough to spend the money.

When a patent expires, anyone can use the idea or make the product. The law considers it public domain. If someone improves on the original patent idea, it could be patented again.

Avoiding Patent Infringement

If you are a business owner or inventor, you need to budget to avoid patent infringement. It's an up-front investment to save you a lot of money in the future. Patent infringement lawsuits are costly and time-consuming. 

Don't think you can't get sued. Patent infringement is a growing field, and many lawyers are willing to take cases on contingency. They don't get paid unless they win the lawsuit. Even if you own a small company, someone could still sue you for patent infringement. 

You are still at risk even if a small business owns the patent. Even if that company can't afford to hire an attorney, it could eventually be bought out by a bigger company which can afford to bring a lawsuit. 

Don't assume you know every patent. Even experts in their fields can't possibly know every new technology or patents for products that aren't on the market. Just because you know a lot about your area doesn't mean you can't unintentionally infringe on someone else's patent. 

Lawsuits and Your Business

Note that you can't play dumb to get out of a lawsuit. In fact, ignoring or pretending a patent doesn't exist sometimes makes you seem more guilty in court.

Lawsuits are problematic for several reasons:

  • Lawsuits are expensive. If you infringe on a patent, you are usually liable for your attorney fees, the patent owner's attorney fees, court costs, damages, and royalties.

  • Your time is precious. Your lawyers will do most of the work, but you still have to meet with your lawyers and appear in court. This can be very time-consuming.

  • A judge might grant a preliminary injunction. This injunction makes you stop making or using the product, and could hurt your business.

  • A lawsuit could damage your company's reputation. Your customers could even be sued in some cases.

  • If you're found guilty, you will have to start over. You will have lost all the time you spent creating the original product.

Be proactive and diligent about patents. Start by searching online for patents using programs like Patent Hunter. Always check your competitors for new technology. Check the packaging of relevant products for any patent numbers. If necessary, simply ask a competitor if they have an existing patent.

Patent Screening

It's expensive to enlist the help of an attorney, but you can curb some of those costs. Thoroughly review any existing patents that could be relevant to your product or idea. Perform your own initial review to remove any patents that may have expired or are invalid. 

Note that written communications are not always considered attorney-client privilege. If you have concerns about a particular patent, don't put it in writing, because it might later be used as proof that you had the knowledge you were infringing on a patent. 

Infringement Review

  • An attorney will offer a preliminary review. This review costs less but does not give an official opinion.

  • If the attorney believes there is a patent infringement concern, then the next step is a formal check. The attorney will check the USPTO file history and look for inaccuracies or reasons the patent might be invalid.

  • Finally, the attorney will do a Patent Invalidity Review, hoping to prove the patent is invalid.

Penalties for Patent Infringement

Preliminary Injunction

If the court finds that the patent infringer is causing damage before or during the case, it could grant a preliminary injunction, which prevents the infringer from continuing his or her actions. 

Permanent Injunction

A court could decide to grant a permanent injunction, or post-trial injunction, if the infringer is found guilty. A permanent injunction makes the guilty party stop his or her actions completely. The court almost always grants a permanent injunction if the infringer is found guilty. 


The court will usually require the infringer to pay damages when he or she is found guilty. These costs might include actual damages, reasonable royalties, or both. The actual damages are the profits that the patent holder lost to the infringer. Royalties depend more on the specifics of the products and the length of the patent.


It's common in patent infringement cases for the infringer to pay costs. These costs include court fees, filing fees, and even the lawyer fees for the patent holder. These costs are usually significant. For example, in 2009, Abbott Laboratories was found guilty of patent infringement for the drug Humira. The courts required Abbott Laboratories to pay the plaintiff, Centocor, $1.67 billion. 

Exceptions and Special Cases

  • It's not considered infringement if the product uses recombinant DNA or RNA or Hybridoma technology. This law also includes genetic manipulation. 
  • If the infringed patent is related to the Food and Drug Administration, the court may make the effective date of penalties fall after the patent expires.
  • In special cases, an injunction against selling a product commercially may reversed if it's an approved drug or biological product for humans or animals.

Hire a Lawyer

If you need help with patent infringement, you can post your question on UpCounsel's marketplace. UpCounsel accepts only the top 5 percent of lawyers to its site. Lawyers on UpCounsel come from law schools such as Harvard Law and Yale Law and average 14 years of legal experience, including work with or on behalf of companies like Google, Stripe, and Twilio