Patent marking isn’t just a legal technicality—it’s a critical step that directly affects your ability to claim damages in a U.S. patent infringement case. Without proper marking, you may forfeit the right to recover retroactive compensation, even if infringement clearly occurred. This post explains how patent marking works, why virtual marking is the most practical solution, and the key risks of non-compliance for both patent holders and licensees. If you're not marking your products—or not updating your list—you may be leaving money on the table.
Patent Granted – Now What?
Congratulations, your published U.S. patent is granted - congratulations! You’re now officially protected when it comes to infringement, right?
Not quite.
If someone is infringing your IP, you want as much compensation for damages as possible. You might assume that this would be enough to be able to undertake action against infringers and receive full compensation for damages; but this is wrong.
If your patent is infringed, and you want to recover damages, you need more than just a granted patent. You must also show that the infringer was actually aware of your patent – which under U.S. law, often means you must mark your products appropriately.
Let’s break down what patent marking means, how to do it right, and what happens if you don’t.
Understanding Patent Marking
Patent marking is the process of giving notice to the public that a product is protected by one of more patents. It is intended to put potential infringers on alert and establish your eligibility to claim damages in a legal dispute. There are two ways to comply with U.S. patent marking laws: traditional marking and virtual marking.
-
- Traditional patent marking – This approach involves marking the patent number directly on the related product itself or on a label, tag or on its packaging. It may be possible to include the marking on product literature associated with the patented product. While this method is straightforward, it becomes burdensome when patents are updated, expire, or when products change—requiring physical modifications to packaging or materials.
- Virtual patent marking - Since 2013, virtual marking offers the same protection as traditional marking but is a more scalable and cost-effective alternative. It involves marking the product 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” (§287(a) AIA). This is practically done by publishing a list of the US patents on the company’s website corresponding to the products offered and putting the URL of the page on the product, data sheets, etc. This digital approach makes it easier to keep patent information up to date. Rather than redesigning packaging every time a patent is granted or expires, businesses can simply update the webpage.
It is important maintain patent markings/websites with up-to-date information by adding new patents and removing outdated ones (because they are abandoned or expired for example), otherwise this creates liability for false marking.
It is important to note that these marking requirements do not apply to patents the include only method claims that are not tied to a specific product.
What is the Effect of Patent Marking on Claiming Damages?
Marking your products correctly isn’t just good practice—it’s legally necessary if you want to recover the full range of damages available in an infringement lawsuit.
Under U.S. law, a patent owner can seek damages for up to six years of infringement prior to the date of the lawsuit…but there’s a catch. If a patent owner has not yet marked its products and the patent has been infringed, the owner will not be able to recover damages unless the infringer was notified and continued to infringe (and even then, the patent owner is only entitled to recover damages from the point the infringer was formally notified).
In most cases, the damages are available because the patent holder marked the product (known as ‘constructive notice’), rather than actual knowledge by an infringer.
Licensees: The Overlooked Liability
Many patent holders assume that if they are marking their products, they’re covered. But, the obligation to mark patents also falls upon licensees.
In Rembrandt Wireless v. Samsung Elecs., the court ruled that Samsung infringed two of Rembrandt’s patents, and Rembrandt was awarded $15.7 million in damages. However, Samsung appealed and argued that Rembrandt licensed one of the patents to a third party - Zhone Technologies - but did not require the licensee to mark its products. The Federal Circuit agreed with Samsung and stated that damages awarded should be reduced to only include the damages suffered after the notice.
Even though Rembrandt did argue that they filed a statutory disclaimer (a statement in which a patent owner relinquishes legal rights to one or more claims of a patent), the Court found this didn’t excuse the lack of marking.
The takeaway? Patent holders must include explicit marking clauses in license agreements and actively verify compliance.
Beyond Damages: Other Benefits of Patent Marking
While legal damages are the primary motivator, proper marking also serves broader strategic purposes. It deters unintentional infringement by clarifying what’s protected. It signals credibility and seriousness to investors, partners, and competitors. And it helps ensure transparency in crowded markets where overlapping technologies are common.
Put simply, marking your patents is about more than litigation—it’s about good business.
Recommendations
If you're not already doing so, now is the time to implement a patent marking strategy:
-
- Review your portfolio: Identify which products correspond to issued U.S. patents.
- Set up virtual marking: Create and maintain a dedicated page on your website listing applicable patents by product.
- Keep it current: Update the list with new patents as they are granted, and remove expired or abandoned ones.
- Audit your agreements: Ensure licensees are contractually required to mark and understand how to do so.
Need Support?
If you’re unsure how to set up a compliant marking system—or want a second set of eyes on your IP strategy—we’re here to help. Stratford’s IP experts can guide you through best practices, licensing risk mitigation, and virtual marking implementation.
Reach out to us to start the conversation.
About the Author:
