Patent Marking Procedure in the United States

Marking your products with the relevant U.S. patent numbers that cover the products is referred to as patent marking. Proper patent marking serves as legal notice to an infringer that allows a patent owner to potentially obtain higher monetary damages in a patent infringement lawsuit by demonstrating earlier notice of patent protection. While patent marking is not required in the U.S., failure to do so can reduce monetary damages awarded in patent infringement lawsuits. Patent marking laws in the U.S. encourage patent owners to give notice to the public that their products are patented, and this can help reduce accidental infringement by competitors who otherwise might not be aware of the patents protecting those products.

U.S. Patent Law

These objectives are achieved because typically, when a patent owner sues a patent infringer, monetary damages are only calculated based on infringing activity that occurred after the infringer receives actual notice of the infringement from the patent owner. Therefore, it is possible that infringing activity may have occurred for a long period of time before the patent owner learned of the offending activity and gave notice to the infringer (e.g., with a warning letter, cease and desist letter, or an actual lawsuit filed with a court), and therefore monetary damages could be very small and unfair to the patent owner. To address such unfairness, U.S. patent law outlines the requirements for proper patent marking, which then serves as constructive notice to the public that a product is protected by one or more patents without having actual knowledge of the patents, and this legally acts as a substitute for actual notice. This U.S. law is outlined primarily in the U.S. Code:

Patentees, and persons making, offering for sale, or selling within the United States any patented article for or under them, or importing any patented article into the United States, may give notice to the public that the same is patented, either by fixing thereon the word “patent” or the abbreviation “pat.”, together with the number of the patent, or by fixing thereon the word “patent” or the abbreviation “pat.” together with an address of a posting on the Internet, accessible to the public without charge for accessing the address, that associates the patented article with the number of the patent, or when, from the character of the article, this can not be done, by fixing to it, or to the package wherein one or more of them is contained, a label containing a like notice. In the event of failure so to mark, no damages shall be recovered by the patentee in any action for infringement, except on proof that the infringer was notified of the infringement and continued to infringe thereafter, in which event damages may be recovered only for infringement occurring after such notice. Filing of an action for infringement shall constitute such notice.

35 U.S.C. § 287(a). As such, monetary damages may be calculated for infringing activities by calculating damages based on the earlier constructive notice date rather than the actual notice date, thereby potentially increasing monetary awards in patent infringement lawsuits. Higher damages in turn deter infringement.

Proper Patent Marking

For constructive notice to occur, proper patent marking procedure must be adhered to. In the U.S., proper marking requires a manufacturer to mark the patented product with the word “Patent” or abbreviation “Pat.” followed by a listing of the applicable patent numbers. The marking should not be concealed, and it should be easy to read. If the actual marking is subject to wear, placement of the marking may be adjusted for the situation. In certain situations, the product may not be suitable for marking (e.g., due to wear or size constraints, or, in the case of a method, there is nothing tangible to mark) and, therefore, marking the product packaging or labeling may be an acceptable substitute. However, simply marking product packaging solely due to convenience or marking product literature that does not accompany the product may not satisfy the requirement for constructive notice.

Virtual Patent Marking

Physically marking the product, packaging, or labeling can be challenging since the listing of patents must be updated from time to time to remove expired patents or add new ones. This can involve significant tooling changes or reprinting costs and require scrapping of old packaging and labeling inventory.

In order to address these challenges, recent changes in U.S. law now also permit virtual patent marking where the product is marked with the word “Patent” or the abbreviation “Pat.” followed by a web address. The web address must be accessible by the public without charge and provide a listing of the relevant patent numbers associated with the patented product. See 35 U.S.C. § 287(a). Virtual marking allows the manufacturer to easily update the schedule of different products and the corresponding patents that cover those products. The website should, at a minimum, show products by brand name and model number followed by a listing of applicable patents specific to those products. Ideally, the patent owner should maintain records that show the website is substantially always available, and the dates any changes were made to the website with records indicating what those changes entailed.

Patent marking is not limited to just the original equipment manufacturer (OEM). Licensees of the patent or contract manufacturers should similarly comply with patent marking requirements for products they produce. Patent marking requirements should be reflected in the patent license or other contracts.

False Patent Marking

Marking a product with a patent that does not cover the product can create liability for the patent owner for false marking. The U.S. Code defines false marking:

(a)Whoever, without the consent of the patentee, marks upon, or affixes to, or uses in advertising in connection with anything made, used, offered for sale, or sold by such person within the United States, or imported by the person into the United States, the name or any imitation of the name of the patentee, the patent number, or the words “patent,” “patentee,” or the like, with the intent of counterfeiting or imitating the mark of the patentee, or of deceiving the public and inducing them to believe that the thing was made, offered for sale, sold, or imported into the United States by or with the consent of the patentee; or

Whoever marks upon, or affixes to, or uses in advertising in connection with any unpatented article, the word “patent” or any word or number importing that the same is patented, for the purpose of deceiving the public; or

Whoever marks upon, or affixes to, or uses in advertising in connection with any article, the words “patent applied for,” “patent pending,” or any word importing that an application for patent has been made, when no application for patent has been made, or if made, is not pending, for the purpose of deceiving the public—

Shall be fined not more than $500 for every such offense. Only the United States may sue for the penalty authorized by this subsection.

(b)A person who has suffered a competitive injury as a result of a violation of this section may file a civil action in a district court of the United States for recovery of damages adequate to compensate for the injury.

(c)The marking of a product, in a manner described in subsection (a), with matter relating to a patent that covered that product but has expired is not a violation of this section.

35 U.S.C. § 292. Thus, improper patent marking potentially opens a manufacturer up to liability for false marking if there is deceptive intent. Other examples of false marking include marking a product with a patent number without consent of the patent owner, using a patent number on an unpatented product, or marking a product with the phrase “Patent Pending” when there is no patent pending. Therefore, ensure the marking, whether on the product, packaging, labeling, or website, is accurate and the patents cover those products. Marking a product with an expired patent is no longer considered false marking under current U.S. patent laws. Additionally, false marking lawsuits to recover statutory damages can no longer be filed by ordinary citizens and only the government is permitted to pursue these suits. An individual that suffers a competitive injury from false patent marketing, however, may sue to recover compensatory damages. Such laws were put in effect following a verdict of no violation of patent marking laws in a lawsuit arguing damages in excess of $10 trillion. See Pequignot v. Solo Cup Co., 608 F.3d 1356 (Fed. Cir. 2010).

Nevertheless, products, packaging, or labeling should be reviewed from time to time to ensure expired patents are removed, new patents are included, and any patents listed do in fact cover the marked products. Having a routine audit program in place to monitor and update patent marking may help a manufacturer demonstrate it did not have intent (a requirement for proving false marking) to falsely deceive the public. Virtual marking provides an easy way of updating product marking without having to change mold tooling or packaging and labeling. However, if the patent marking is included in tooling, manufacturers should consider using removable inserts that have the marking information and can be easily updated and replaced when needed rather than having to make an entirely new tool.


Marking your product with patents that cover the product provides constructive notice to the public that the product is protected by one or more patents. Constructive notice may allow the patent owner to obtain higher monetary damages when there is patent infringement. Having incorrect patent marking information can render a manufacturer liable for false marking, but seemingly only if there was deceptive intent. Thus, effective patent marking requires routine monitoring and updating to ensure the information is accurate and up to date.

Please contact our team of intellectual property attorneys if you have any questions or wish to discuss a U.S. patent marking plan that can best fit your needs.

Attorney Advertising. Prior results do not guarantee a similar outcome. This publication is provided as a service to clients and friends of Harter Secrest & Emery LLP. It is intended for general information purposes only and should not be considered as legal advice. The contents are neither an exhaustive discussion nor do they purport to cover all developments in the area. The reader should consult with legal counsel to determine how applicable laws relate to specific situations. ©2023 Harter Secrest & Emery LLP