Patent Marking

A Guide for Business Owners

Patent marking is the practice of labeling products with patent information, typically the word “Patent” or “Pat.” followed by a patent number, to notify the public that the product is protected by an issued patent. For business owners new to patent law, understanding patent marking is crucial. Proper marking serves multiple purposes: it provides notice to the public of a product’s patent protection, helps preserve the patent owner’s rights to recover damages for patent infringement, and can deter competitors from copying the patented invention. In the United States, while patent marking is technically optional, it is highly recommended as a best practice for anyone who sells a patented product and may need to enforce their patent rights. This article offers an overview of U.S. patent marking laws, the benefits of marking, how to mark products (including “patent pending” notices and virtual marking), and the pitfalls of false marking.

Executive Summary: Patent Marking for Businesses

Patent marking—labeling products with “Patent” (or “Pat.”) and the patent number—alerts the public that an item is protected. While optional under U.S. law (35 U.S.C. § 287), it’s a best practice for businesses selling patented products. Proper marking provides constructive notice, deters competitors, and preserves the patent owner’s right to claim damages for infringement dating back up to six years.

If a product isn’t marked, damages are limited to infringement after actual notice (e.g., a lawsuit or cease-and-desist letter). Marking is especially important for physical products covered by apparatus or design patents. For method-only patents, marking isn’t required, but damages still depend on notifying infringers.

Two marking options exist:

• Physical marking: Affix “Patent” and applicable numbers on the product or packaging, ensuring visibility and durability.
• Virtual marking: List a web address on the product leading to a webpage associating patents with products. The site must be public, clear, and regularly updated.

Best practices include marking all units consistently, updating for new or expired patents, requiring licensees and manufacturers to mark, and keeping detailed records.

False marking, claiming “patent pending” without an application, or listing unrelated patents—can lead to legal exposure. Since 2011, penalties require proof of intent to deceive or competitive injury, but honest mistakes (like marking expired patents) are no longer penalized.

In short, marking patented products protects your rights, strengthens enforcement, and helps recover full damages in infringement disputes.

The Purpose and Benefits of Patent Marking

Patent marking exists primarily to give constructive notice of patent rights to the public. By marking patented articles, a patent holder effectively warns others that the product is under patent protection, thereby reducing accidental infringement by those who might unknowingly copy or use the invention. This advance notice can foster an atmosphere of respect for innovation and encourage competitors to design around the patent rather than infringe it. Marking also preserves the patent owner’s ability to claim damages from the earliest possible date of infringement. Under U.S. law, if products are properly marked, the patent owner may recover monetary damages for up to six years of past infringement (the maximum statute of limitations) prior to filing a lawsuit. Without marking, those monetary damages could be severely limited.

Key benefits of patent marking:

• Public Notice and Deterrence: It puts the public on notice that an item is patented, helping prevent accidental infringement by parties who might otherwise be unaware of the patent. All potential infringers are considered to be under constructive notice, which allows the patent holder to pursue patent infringement damages against an infringer even if they are unaware of the infringement.
• Preservation of Damage Claims: It ensures that the patentee can recover damages from the moment infringement begins, not just from when the infringer is formally notified (actual notice). In other words, effective patent marking allows the patent holder to capture all infringement occurring before a lawsuit or cease-and-desist letter, up to the legal time limit.
• Competitive Advantage: Marking underscores the product’s exclusivity and can dissuade competitors, thereby strengthening the patent owner’s market position.
• Facilitating Licensing: A properly marked patent can signal to potential partners that the patent is active and enforced, lending credibility in licensing agreements or negotiations.

By contrast, not marking a patented product can result in lost opportunities to claim patent infringement damages and may invite uninformed parties to infringe, unaware of the patent. In summary, patent marking is a simple step that significantly bolsters a patentee’s patent rights enforcement and patent protection strategy.

U.S. Patent Marking Law – Constructive Notice

The U.S. patent marking statute, 35 U.S.C. § 287(a), establishes the patent marking requirements and the consequences of non-compliance. In essence, the law encourages patentees to mark their products by limiting damages for unmarked products. The statute provides that patentees, and persons making or selling any patented articles, may give notice to the public that the item is patented by marking it accordingly. Specifically, the patent owner should either fix “Patent” (or “Pat.”) and the patent number to the product or, if the article’s size or nature makes physical marking impracticable, affix the information on the packaging in a manner that provides like notice. This marking serves as constructive notice to the public that the article is patented.

Under § 287(a), if a patent owner (or its licensee or manufacturer) fails to mark a patented product, no damages can be recovered for patent infringement that occurred before the infringer was given actual notice of the infringement. In other words, absent marking, the patentee’s damages are limited to infringement occurring after such notice is given to the infringer. Actual notice usually takes the form of a specific communication to the alleged infringer, such as a cease-and-desist letter or the filing of an infringement lawsuit. Importantly, the infringer’s actual knowledge of the patent is not a substitute for the patent holder’s compliance with the marking statute. The law imposes an affirmative duty on the patent holder to mark; even if an infringer knew about the patent, the patent owner still cannot claim damages for earlier infringement without either marking or proving they gave actual notice. As one court explained, the marking notice provisions focus on the patent holder’s conduct, not the infringer’s knowledge.

These marking requirements apply to physical products that are covered by patent claims. Notably, patents on processes or methods are treated differently under the law. For now, the key point is that U.S. patent law offers a carrot-and-stick approach: marking is not mandatory (the statute says a patentee “may give notice” by marking), but failing to mark a patented invention comes with the penalty of forfeiting certain patent rights – specifically, the right to collect past damages prior to notice. Companies seeking to fully enforce their patents and obtain monetary damages for infringement should pay careful attention to these patent marking laws.

“Patent Pending” vs. “Patented” – Marking During Patent Application Stage

You may have seen products labeled “Patent Pending” or “Patent Applied For.” This indicates that a patent application has been filed for the product but a patent has not yet been granted. Marking an item as “patent pending” is permitted during the application process and can serve as a deterrent to competitors by signaling that patent protection is being pursued. However, it is crucial to understand that patent pending status does not confer any enforceable patent rights, one cannot sue for infringement until the patent actually issues. The marking is purely a cautionary notice. Once the patent is granted, the product must be updated to display the patent number (either physically or via virtual marking) to meet the formal marking requirement. Continuing to use “patent pending” after a patent issues, or failing to switch to the actual patent number, can lead to non-compliance with marking regulations and a failure to provide constructive notice.

Equally important is the truthfulness of a patent-pending claim. U.S. law prohibits false claims of patent pending status. According to 35 U.S.C. § 292(a) (false marking statute), it is illegal to mark an article with “patent applied for” or “patent pending” or similar terms when no application is in fact pending, if done with intent to deceive the public. For example, a company should never label a product as “patent pending” if it has not filed a patent application, or if the application was abandoned, as that would constitute false marking. Violations can incur penalties. In practice, as soon as a patent is granted, the marking should be changed from “pending” to “Pat. [Number]”; and if a patent application is abandoned or rejected with no continuing applications, any patent pending labels should be removed to avoid misleading the public. Likewise, if a patent expires, the product should no longer be marked as patented. Continuing to mark an expired patent could be considered misleading.

How to Mark Patented Products: Physical Marking

Traditional physical marking involves affixing patent information directly onto the patented article or its packaging. The marking should include the word “Patent” or the abbreviation “Pat.” followed by the applicable utility patent numbers for the product. For example, a label might read “U.S. Patent No. 10,000,000” or simply “U.S. Pat. 10,000,000.” If multiple patents cover the product, it is common to list each relevant patent number (e.g., “Pat. 9,500,000; 10,000,000”). In the case of design patents, the format “Pat. D123,456” is often used (the “D” indicating a design patent). The goal is to clearly identify which patents cover that product.

Proper marking should be legible and placed where it can be readily seen by the consumer or anyone inspecting the product. The U.S. statute suggests marking the article itself “by fixing thereon” the required information, but it acknowledges that sometimes marking the product directly is not feasible. For instance, if the product is very small, has a surface that cannot easily be stamped or labeled, or if marking it would damage its functionality or aesthetics, then attaching the patent notice to the product’s packaging is acceptable. In those cases, fixing a label with like notice on the package is deemed sufficient as long as the product is sold with that packaging. Manufacturers should ensure the markings are durable (for example, etched, molded, or printed indelibly, if possible) and not easily removable or hidden. If the product is prone to wear or the marking could be worn off, marking the package might be preferred to maintain visibility. What matters is that someone looking at the product or its packaging will receive notice to the public that the item is patented.

Some practical tips for physical marking:

• Visibility: Place the patent notice in a conspicuous spot. Common locations include the product’s label, base, or an area that consumers routinely see. Avoid obscure internal components unless no alternative exists.
• Consistency: Consistently mark all units of the patented product. To satisfy the law, substantially all products being sold must be marked. Sporadic or half-hearted marking (marking only some batches and not others) can undermine the ability to claim constructive notice. The marking requirement generally expects patentees to mark products consistently once they begin marking, so establish a routine process to ensure every item (or its package) goes out properly marked.
• Packaging as a Solution: If the product itself cannot be easily marked (due to size or material), mark the packaging or a hang-tag that is attached to the product. However, the marked packaging must remain with the product through sale, if products are sold individually without the package (e.g., a small component taken out of a marked box and sold loosely), then the notice might not reach the end user. In such cases, alternative solutions (e.g., tiny tags or inserts) should be considered.
• Updates for New or Expired Patents: Keep the marking current. If new patents issue that cover the product, add those patent numbers to the marking, or if space is limited, consider switching to virtual patent marking discussed next. Likewise, if a patent expires or is held invalid, promptly remove or alter the marking to avoid confusion or false marking issues. It is good practice to include patent markings as part of product version control and compliance checklists.

By following these practices for physical marking, companies can ensure effective patent marking, meaning the marking accomplishes its purpose of providing legal notice while also complying with the statute’s specifics.

Virtual Patent Marking

Virtual patent marking is a modern alternative to stamping patent numbers on products. It was introduced by the America Invents Act (AIA) in 2011 to simplify marking in the digital age. With virtual marking, a product may be marked with an internet address (URL) that leads to a webpage listing the patents associated with that product, instead of listing out patent numbers on the product itself. For example, a label on the product might read: “Patents: www.company.com/patents”. The statute was amended to allow marking by “fixing thereon the word ‘patent’ or ‘pat.’ together with an address of a posting on the Internet” that associates the patented article with its patents. This approach provides flexibility, especially for products covered by many patents or when patents change frequently.

Requirements for a valid virtual marking are:

• The URL must be publicly accessible without charge and clearly identify the relevant patents. The web page should explicitly list patent numbers next to or under the product model or name, so that someone visiting the page can readily see which applicable patent numbers correspond to the product.
• The marking on the product or package should use a phrasing that indicates it’s a patent notice and points to the URL (e.g., “Patent: company.com/patents” or “Pat. www.company.com/123”). Simply printing a company homepage without context is not sufficient. Likewise, the page that the URL points to must not require navigation or searching to find the patent information. Courts have held that a generic homepage or a bare list of patents is inadequate. In one case, a URL that led only to a general patents list on a company’s website (making the user hunt for which patents matched the product) was deemed insufficient notice. The Western District of Texas criticized a patent owner for using a homepage link that forced a “research project” on the user to find the relevant patents, which did not meet the notice standard.
• Each patented product should be clearly tied to its patent number(s) on the site. For instance, a table or list could show product names or SKUs alongside the patents that cover them. Simply listing a bunch of patent numbers with no indication of which product they pertain to will not give effective notice. A Massachusetts court found a virtual marking defective when the webpage only provided a table of patent numbers and titles without saying which products those patents covered. The takeaway is that clarity and specificity on the website are essential for effective patent marking via virtual means.

Virtual marking offers several benefits for companies. It allows quick updates: as soon as a new patent issues or one expires, the webpage can be edited, ensuring you always provide up-to-date information without having to retool a production line. It is also efficient for products that have dozens of patents – instead of trying to list all those numbers on a small device, the single URL covers all of them. Additionally, one URL can cover multiple products and multiple patents in a centralized place. This can save cost and effort, especially for high-tech products or software-related inventions. In fact, software and digital products often rely on virtual marking because there may not be a traditional “label” or physical medium to mark within the software interface itself. For example, software might display an “About” box or a section in settings with patent information, or provide a link to a patents webpage.

To implement virtual marking correctly, companies should create a dedicated patents page on their website, keep it organized (group patents by product or category), and ensure the URL on the product is permanent and easy to type. Using a simple URL or a QR code (with a short URL embedded) can be helpful, though courts have not definitively ruled on QR codes yet. Importantly, document your virtual marking efforts. Maintain dated archives of your patent webpage (even using web archive tools) so you can later prove in court what information was provided at a given time. This kind of evidence can be crucial to show you complied with marking requirements throughout the period of infringement.

In summary, virtual patent marking is a powerful tool that, when done properly, satisfies legal requirements and provides notice just as physical marking does. It’s particularly useful when dealing with many patents or when dealing with intangible products, but it requires diligence to set up and maintain.

Best Practices for Patent Marking Compliance

Whether using physical or virtual marking (or both), a patent owner should follow best practices to ensure compliance and maximize the benefits of marking:

• Accuracy and Clarity: Always use the correct patent numbers and ensure they correspond to the product in question. Double-check the numbers for typos. Use clear wording like “Pat.” or “Patent” so there’s no ambiguity that this is a patent notice. Avoid confusing or vague language. Clarity is not just good for the public; it also protects against challenges that your marking was insufficient.
• Consistency and Coverage: Mark all instances of the patented product that are sold or distributed. The law expects patentees to make reasonable efforts to mark substantially all patented articles. For example, if you have contract manufacturers or various production batches, each should include the marking. One unmarked unit in an ocean of marked units might not destroy your claim (courts generally require substantial compliance, not 100% perfection), but a pattern of unmarked sales will forfeit your constructive notice. Develop internal processes or checklists to consistently mark products and packaging across manufacturing sites and licensees.
• Documentation: Keep records of when marking began for each product, how it is done, and samples of marked products or packaging. Photographic evidence of representative marked products, copies of packaging, and printouts or snapshots of virtual marking webpages at various dates can serve as proof of compliance. In patent litigation, the burden may fall on the patent owner to prove that marking was properly done if the infringer challenges it. For instance, documenting changes when new patents are added or when a patent expires (and thus is removed from the marking) will show diligence.
• Licensing Agreements and Manufacturer Contracts: If you license your patent to others or use contract manufacturers, include a clause requiring them to mark products in accordance with § 287. The Federal Circuit has made it clear that licensees’ products must be marked, and the patent owner has a duty to police this. In Arctic Cat Inc. v. Bombardier Rec. Prods. Inc., the patent owner’s failure to ensure its licensee marked the patented articles cost the patentee some pre-suit damages. The court held that patentees must make reasonable efforts to ensure licensees and others under their control comply with marking laws. Thus, it’s wise to put the obligation in writing and periodically follow up with licensees to confirm compliance. In short, patent marking obligations extend to “persons making or selling” under the patentee’s authority, not just the patentee itself.
• Global Considerations: If you sell products internationally, note that marking rules differ by country. The U.S. marking statute doesn’t directly apply abroad, but some countries have their own requirements or incentives. For example, foreign counsel may advise marking in certain jurisdictions to avail specific remedies. Also, you might mark a product with multiple countries’ patent numbers (e.g., U.S., EU, Japan) to cover all bases. Just ensure the information is up to date for each region. The focus of this article is U.S. law, but remember to consult local laws for products sold outside the U.S. (many countries do not require marking for damages, but a few do in limited ways).
• Avoid Over-Marketing: Only mark products with patents that actually cover them. Do not list patents that are only tangentially related or list every patent you own hoping to scare off competition. Over-marking could backfire by inviting allegations of false marking if some listed patents don’t actually cover the product. Stick to applicable patent numbers for that product.

By adhering to these best practices, businesses can maintain an effective patent marking program. The payoff is twofold: you put the world on notice of your patents (strengthening your legal position and deterring infringement) and you ensure that you preserve your ability to collect full event damages should litigation arise (meaning you won’t leave money on the table due to a technical marking omission).

Marking Requirements for Different Types of Patents

Not all patents are alike, and the marking rules reflect that. The statute refers to marking “patented articles,” which naturally covers patents that have at least one product or apparatus claim. Here’s how marking requirements break down by patent type:

• Product (Apparatus/System) Patents: These cover tangible inventions (machines, devices, compositions, etc.). If you have an apparatus or system claim and you make or sell a corresponding physical product, you should physically mark or virtually mark that product. Design patents, which protect ornamental designs of physical items, also fall in this category, they have physical embodiments, so marking the product (or the packaging as discussed herein) with the design patent number is required for full damages. Essentially, any patent that results in a physical product being sold should be marked in some form.
• Method (Process) Patents: Patents that have only method claims (i.e. they protect a process or method of doing something, and not a tangible thing) have no marking requirement. You cannot mark an intangible method; there is no physical article to put a label on. U.S. courts, including the Federal Circuit, have been clear that § 287’s notice requirement “do[es] not apply where the patent is directed to a process or method”. For instance, if you have a patent on a method of manufacturing a chemical but you do not sell a product, you simply license others to use the method, there’s no need (and no way) to mark. However, keep in mind that if someone infringes a method patent, you must provide them actual notice of infringement (e.g., by a letter or lawsuit) to start accruing damages, because constructive notice via marking wasn’t possible. In other words, unmarked method patents can still get damages, but only from the point of actual notice, since marking is excused by the nature of the patent.
• Mixed-Claim Patents (Both Apparatus and Method Claims): Many patents contain both system/apparatus claims and method claims. These cases are tricky. The law says if a patented article (covered by an apparatus claim) is sold, it must be marked to claim damages. If a patent holder is asserting both apparatus and method claims from the same patent, failing to mark the product will prevent recovery of damages for any patent infringement prior to notice, effectively penalizing the patentee for non-compliance across the board. Interestingly, patent holders have sometimes tried to work around this by only asserting the method claims in litigation, especially if they did not mark the product. By suing only on method claims, they argue the marking statute shouldn’t apply (since the lawsuit is technically about a method) and thus they can still get past damages despite unmarked products. Courts have had to grapple with this scenario. The Federal Circuit has allowed this tactic so far, since marking is tied to the claims being asserted, a patentee can “choose” to sue on method claims and avoid the marking requirement, even if the patent also has apparatus claims. One Federal Circuit decision noted that “the notice provisions of § 287 do not apply where the patent is directed to a process or method”, which has been interpreted to mean if you assert only method claims, the marking statute doesn’t cut off your damages.
• Gamesmanship Concerns: However, this workaround has its critics. The practice of basing the marking requirement on a patent holder’s litigation strategy rather than on the fact that a product was actually covered by a patent is legally dubious. Allowing the determination of whether past damages are available hinge on whether the patent holder asserts an apparatus claim or not, seems to favor the private patentee's recovery over public notice, and to be inconsistent with patent law policy. The patented product ought to be marked regardless of which claims are sued upon. Regardless, the safe course for patent owners is to mark products even if the patent also has method claims, so you’re protected no matter which claims you need to assert.

In summary, apparatus claims (including system and design patents) demand marking of products, whereas method claims do not. If your patent has both, it’s wise to mark any related products to avoid complexity. Always err on the side of providing notice, the effort to mark is usually far less trouble than the complications and limits that arise from not marking.

Consequences of Failing to Mark

Failing to comply with the patent marking requirements can significantly impact a patent owner’s enforcement rights. The primary consequence is the limitation on recoverable damages. As discussed, if a patented product was not marked, the patent holder cannot collect damages for infringement that occurred before the infringer received actual notice of the infringement. This can mean a drastic reduction in the compensation the patentee recovers. For example, imagine a competitor has been selling an infringing product for three years before the patent owner discovers it. If the patent owner’s own product wasn’t marked during that time, the owner might only be able to recover damages from the point they notify the infringer (say, via filing the lawsuit) onward, those first three years of infringement could be money lost forever. By contrast, had the product been marked, the patent owner could potentially claim damages for the full three years (and up to three more, since patent law generally allows up to six years of back-damages).

Another consequence is more strategic: not marking might embolden potential infringers. Without a marking, competitors or other parties might not realize your product is patented (no notice to the public), and thus they might inadvertently or even intentionally copy it, thinking it’s safe to do so. While ignorance of a patent is not a defense to infringement, it does remove liability for damages before notice and it also removes the threat of enhanced damages for willfulness in that early period. Essentially, not marking can lead to accidental infringement or surreptitiously intentional infringement by others and leaves you with fewer remedies against them. Marking, on the other hand, can prevent that scenario by making your rights visible from the start.

Courts have also clarified procedural aspects of the marking defense. Once an infringer raises a challenge that a patentee sold unmarked products, the burden can shift to the patent owner to prove compliance. The Federal Circuit in cases like Arctic Cat has outlined that an alleged infringer must first identify specific products that were unmarked and covered by the patent; then the burden shifts to the patentee to show those products were marked or that the patent owner made reasonable efforts to ensure marking. If the patentee cannot show consistent marking or efforts to mark, pre-notice damages will be disallowed.

It’s worth noting that if a patent owner never made or sold any product covered by the patent (for instance, a purely licensing entity or an inventor who hasn’t commercialized the invention), then § 287’s marking provisions do not apply. In such cases, the patentee can still collect damages for up to six years prior to filing suit, because the law only restricts damages when there was a product that could have been marked. Similarly, if infringement is of a method claim only (and no product to mark), the damages can accrue from infringement without marking (subject to actual notice requirements). But these are exceptions to the general rule. Most practicing entities (companies making products) should assume marking is necessary.

In sum, damages awarded for past infringement can be severely affected by a failure to mark. The patent marking requirement is thus not something to overlook. The relatively simple act of marking products can be the difference between recovering a full measure of damages versus losing out on potentially substantial sums of money.

False Patent Marking and Its Prohibition

While patent marking is encouraged, false marking is strictly prohibited. False patent marking refers to labeling products in a misleading way regarding patent protection, with intent to deceive the public. There are a few forms this can take, all addressed by 35 U.S.C. § 292:

• Marking an unpatented article as patented. In other words, claiming a product is patented (with a patent number or the word “patent”) when it in fact has no patent coverage. This includes marking a product with a patent number that doesn’t cover the product or using the word “patent” when the product has no patents at all.
• Using “patent pending” or “patent applied for” when no patent application is in process (or the application has been abandoned/withdrawn), with intent to deceive.
• Marking a product with someone else’s patent or a fake patent number to imply endorsement or license by the patent owner, done to deceive consumers into thinking the product has authorized patent protection. This scenario is less common, but the statute covers using the name or patent of another without consent, intending to deceive.

Originally, false marking was considered a serious offense with steep penalties, historically up to $500 per offense, which courts interpreted as per falsely marked article. This led to a wave of false marking lawsuits around 2009-2011, where enterprising individuals (non-competitors) sued companies for marking products with expired patents or incorrect patent numbers, seeking massive fines. For instance, companies were sued for not removing old patent numbers from products after the patents expired (expired patents technically made those products “unpatented” in the eyes of the law). The Forest Group v. Bon Tool, 590 F.3d 1295 (Fed. Cir. 2009) case confirmed the per-article fine, incentivizing a cottage industry of “marking trolls.” Another notable case, Pequignot v. Solo Cup, 608 F.3d 1356 (Fed. Cir. 2010), involved a manufacturer that kept molding patent numbers into cup lids even after the patents expired, the court held that while the lids were falsely marked (expired patent = unpatented article), the manufacturer avoided penalty by proving it had no intent to deceive: they were trying to save cost on changing molds, not trick the public. This case established that intent to deceive is a required element: honest mistakes or continued use of old markings without deceptive intent are not penalized.

In response to the explosion of opportunistic lawsuits, Congress reformed the false marking law in the AIA of 2011. The changes, reflected in 35 U.S.C. § 292(b)-(c), are:

• Only the U.S. government can sue for the civil penalty (fine) for false marking; the qui tam provision (which allowed anyone to sue and split the penalty) was eliminated. This effectively shut down the wave of bounty-hunter lawsuits.
• Private parties can still sue, but only if they have suffered a competitive injury as a result of the false marking. In such cases, the remedy is not the $500 per article fine, but rather damages adequate to compensate for the injury. This means a competitor who lost sales or was hurt in the market due to a rival’s false marking can seek damages for that harm (perhaps because consumers thought the rival’s product was superior for being “patented”).
• Marking a product with an expired patent is no longer a violation of the law. This was a significant safe harbor added by the AIA, recognizing that continuing to mark an expired patent (which was once valid) should not be punished; it’s often inadvertent or harmless once the patent is public domain. Therefore, as of 2011, you cannot be fined or sued under § 292 simply for failing to take old patent numbers off your product after the patent expires.

Even with these changes, false marking is something companies want to avoid. While the threat of random plaintiffs suing has gone away, a competitor could still bring a claim if they can show competitive injury. Moreover, false marking can also draw scrutiny under other laws, such as unfair competition or truth-in-advertising statutes. In a recent Federal Circuit case, Crocs, Inc. v. Effervescent, Inc., 119 F.4th 1 (Fed. Cir. 2024), the court allowed a claim to proceed under the Lanham Act, which governs false advertising, for a company’s marking of products with expired patents. Even though marking expired patents isn’t a § 292 violation anymore, the competitor in that case alleged that doing so was misleading to consumers, essentially a false advertising claim. The Federal Circuit’s decision suggests that blatantly misleading patent markings (e.g. using very old patent numbers to imply a product is patented when it’s not) could be challenged as false advertising, leading to competitive injury liability under the Lanham Act. The best practice is still to ensure your patent markings are truthful and up-to-date to avoid competitive injury claims or reputational harm.

Conclusion

Patent marking may seem like a minor detail in the grand scheme of patent strategy, but it has outsized importance in U.S. patent enforcement. For business owners and attorneys unfamiliar with the process, the key takeaways are: mark your patented products (physically or virtually) to put the world on notice of your rights; doing so preserves your ability to collect full damages if you have to sue for patent infringement. The purpose of marking is to provide public notice (constructive notice) of your patent, which in turn strengthens your hand against infringers and promotes respect for your innovation. Be mindful of the patent marking requirements under 35 U.S.C. § 287, they require marking as a condition to recover certain patent infringement damages. Always ensure your marking is accurate and up-to-date: use “patent pending” only when appropriate, switch to patent numbers once issued, and remove markings when patents expire or no longer apply. Improper marking not only jeopardizes damages but can lead to false marking liability if done with intent to deceive. The law has evolved (especially after the AIA) to curb abuse of false marking claims, yet honesty in marking remains the best policy to avoid any competitive injury claims by rivals.

By understanding and adhering to patent marking laws, patent holders can ensure their innovations are not only protected by patents on paper, but that their patent protection is practical and enforceable in the market. If you have questions about patent enforcement or other intellectual property matters, please contact our office for a free consultation.

© 2025 Sierra IP Law, PC. The information provided herein does not constitute legal advice, but merely conveys general information that may be beneficial to the public, and should not be viewed as a substitute for legal consultation in a particular case.