Key Takeaways

  • To define infringement of patent, it occurs when someone makes, uses, sells, or imports a patented invention without the patent holder’s authorization. Courts rely on patent claims, Markman hearings, and the Doctrine of Equivalents to decide cases.
  • Patent standing requires that the patent owner, or in some cases an exclusive licensee, bring the infringement action in federal court. Co-owners must join the suit, and non-exclusive licensees cannot sue independently.
  • Patent infringement notices are crucial because damages may only be recovered if the alleged infringer had actual notice of the patent. This can be provided through marking, litigation, or a cease-and-desist letter.
  • The American Inventor’s Protection Act (AIPA) created provisional rights for published but not yet issued patents, provided the infringer had actual notice and the claims remain substantially similar.
  • Infringement can be direct, indirect, induced, or willful, each with different standards and penalties. Willful infringement may lead to treble damages.
  • Remedies for infringement include injunctions, compensatory damages, lost profits, reasonable royalties, and sometimes enhanced damages or attorney’s fees.
  • A patent infringement notice should be drafted carefully, balancing enforcement with the risk of triggering a declaratory judgment action in an unfavorable venue.

What Is a Patent Infringement?

A patent infringement notice is sent to an individual or a business that has made, imported, used, or sold a creation already patented in the United States. The person in question may have actively infringed on a patent. Alternatively, the person or the business may be a contributory infringer who sells a product knowing it is based on patent infringement. The claims in a patent determine the level to which the invention is protected from infringement. The court uses the broadest valid claim to decide if infringement has occurred.

For utility patents that have possibly been infringed upon, the trial judge is responsible for defining the patent's claims. If the meanings he or she assigns are contested, a Markman hearing is held to define the patent's scope. This often includes expert testimony about the patent or its associated industry. 

If the differences between the patent and the infringing product in question are minor, the court may use the Doctrine of Equivalents. This document is used as a guide to detect insubstantial changes to the creation that are designed solely to avoid technical infringement.

Types of Patent Infringement

Patent infringement can take several forms, and understanding the distinctions helps define infringement of patent more precisely:

  • Direct Infringement – Occurs when a party makes, uses, sells, or imports the patented invention without permission.
  • Indirect Infringement – Involves contributing to or inducing another party’s infringement. For example, selling a component specially made for use in a patented product may qualify.
  • Contributory Infringement – Supplying a part that has no substantial non-infringing use, with knowledge of its infringing purpose.
  • Induced Infringement – Encouraging or aiding another to infringe, such as through instructions or marketing.
  • Willful Infringement – When infringement is deliberate and knowing, courts may award enhanced damages up to three times the actual amount.

Patent Standing

Patent owners are responsible for enforcing their own patent rights. If an infringement occurs, he or she can file a civil action against the perpetrator in federal court. The party in question can appeal this action through the Federal Circuit Court of Appeals. If two or more parties co-own the patent, all parties must join any infringement suit. If the patent has been assigned, the assignor no longer has the right to enforce the patent. However, the assignee can independently file an infringement action. 

A licensor is not legally obligated to protect a patent licensee against infringement. However, an exclusive licensee can file an infringement suit without the licensor. A non-exclusive licensee must file with the licensor as a co-plaintiff.

Remedies and Penalties for Infringement

If infringement is proven, courts may impose a range of remedies:

  • Injunctions – A court order stopping the infringer from making, selling, or using the product.
  • Damages – These include lost profits or, at minimum, a reasonable royalty based on hypothetical negotiations between the parties.
  • Enhanced Damages – Up to triple damages may be awarded in cases of willful infringement.
  • Attorney’s Fees – In exceptional cases, courts may order the infringer to pay the patent holder’s legal costs.

The goal is to restore the patent owner to the financial position they would have enjoyed had the infringement not occurred.

Infringers Need to Receive a Patent Infringement Notice

In some cases, the patent owner can recover royalties that accumulate between the patent application's publishing date and the date the patent was issued. These provisional rights are in effect when the infringer received notice of the published patent. In a 2015 Delaware case, the court held that evidence showing that the accused infringer should have known about the published patent does not necessarily show that he or she had actual notice. Thus, provisional rights are not valid unless actual notice can be established.

Strategic Considerations in Sending Notices

Patent holders must weigh the risks of sending a patent infringement notice. While it establishes “actual notice” necessary for damages, it may also give the alleged infringer grounds to file a declaratory judgment lawsuit in a less favorable court.

To mitigate risks, many patent owners:

  • Send carefully drafted notices that assert rights without overcommitting.
  • Use formal cease-and-desist letters only when prepared for litigation.
  • Consider marking products with the patent number, which automatically provides constructive notice and strengthens future claims.

Patent Infringement Notice: Background

In 1999, the passage of the American Inventor's Protection Act (AIPA) provided patent applicants protection for infringement that occurs after the patent is published but before it is issued. According to this federal law, the accused infringer must:

  • Be selling or have sold an identical invention
  • Have received actual notice of the published patent in question 

Under AIPA, however, it can be difficult to show the claims are substantially similar to those in his or her patent application.

Patent Infringement Notice Requirement

For a patent to receive provisional protection, the patent owner must prove the infringer had "actual notice" of the published patent. This must take the form of:

  • Marking the product with the patent number
  • Filing an infringement action
  • Receiving a cease and desist letter 

It does not matter whether the infringer knew about the patent if he or she did not receive specific notice through one of those three methods. 

The best way to provide actual notice is by marking the product with its patent number. If the product in question has this marking, the patent owner can receive damages for infringement back to the date of the marking (a maximum of six years). He or she can also receive damages from the date on which a cease and desist letter was sent to the infringer, or the date when an infringement action was filed in civil court, provided that infringement continues after that date.

Keep in mind that if you send a cease and desist letter to a patent infringer, he or she may respond by bringing judgment against you in an unfavorable district. For this reason, consider skipping this step and filing an action in a favorable district.

Defenses Against Patent Infringement

Accused infringers can raise several defenses, including:

  • Non-infringement – Arguing the product or process does not fall within the patent’s claims.
  • Invalidity – Challenging the patent’s validity due to prior art, obviousness, or insufficient disclosure.
  • Patent Exhaustion – Claiming the patent rights were exhausted after an authorized sale.
  • Experimental Use or Fair Use – Limited exceptions for non-commercial, research-related uses.

These defenses highlight that defining infringement of patent rights also depends on whether the patent itself withstands scrutiny.

Frequently Asked Questions

  1. How do courts define infringement of patent? Courts compare the accused product or process to the patent’s claims, often with expert input and a Markman hearing.
  2. What is the difference between direct and indirect infringement? Direct infringement involves making or selling the patented invention, while indirect infringement covers aiding, inducing, or supplying components for infringement.
  3. Can a patent be enforced before it is granted? Yes, under the AIPA, provisional rights may apply if the infringer had actual notice of the published application and the issued claims are substantially the same.
  4. What damages can a patent holder recover? Damages may include lost profits, reasonable royalties, and in willful cases, enhanced damages up to three times the actual amount.
  5. What are common defenses against infringement claims? Defenses include non-infringement, invalidity, prior art challenges, and patent exhaustion.

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