Product Companies
Patent Marking
If you sell a patented product and don't mark it correctly, you may lose years of infringement damages. If you mark it incorrectly, you face false-marking liability. Here is everything a product company needs to know.
Why marking matters: the damages consequence
Patent marking is governed by 35 USC § 287. The statute says: if you make, offer for sale, or sell a patented article and fail to mark it, you cannot recover damages from an infringer for the period before the infringer had actual notice of the patent.
In practice: if your product has been sold unmarked for two years, and you then discover an infringer who has also been infringing for two years, you can only recover damages from the date you notified the infringer. The two years of prior infringement damages are gone.
This is a significant and commonly overlooked risk. Many patent holders obtain patents but never implement a marking program. When they eventually enforce the patent, they discover their damages have been dramatically curtailed.
Two ways to mark: physical and virtual
Physical marking
Affix the word 'Patent' or abbreviation 'Pat.' followed by the patent number(s) to the product itself or to its packaging. The marking must be visible and legible. For products too small to display the patent number, mark the packaging. For products where direct marking is impractical (e.g., industrial chemicals sold in bulk), mark the closest practicable container or label.
Virtual patent marking (post-AIA, 2011)
The America Invents Act authorized virtual marking: affix 'Patent' or 'Pat.' followed by a URL (e.g., 'patent: patentbrief.org/patents') on the product. The URL must lead to a freely accessible page listing which patents cover which products. No charge to access. The listed patents must be accurate and updated promptly when patents issue, expire, or are found invalid. Virtual marking is now standard for technology products covered by many patents.
What 'Patent Pending' means — and what it doesn't
Once any patent application is filed — provisional or non-provisional — you may mark the product 'Patent Pending' or 'Patent Applied For.' These phrases are equivalent.
Patent Pending has NO legal enforcement power. It does not give you the right to exclude anyone from making or selling the product. Only an issued patent gives you that right. Patent Pending is a notice signal: it tells competitors that a patent may be coming, which can deter some copying.
For pre-issuance damages: under 35 USC § 154(d), if your published application contains a claim that is substantially identical to a claim in the eventually issued patent, you may collect reasonable royalties for the period from publication to grant — but only if the infringer had actual notice of the published application.
Falsely marking a product 'Patent Pending' when no application has been filed is a federal crime under 35 USC § 292(a).
False marking: what to avoid
False marking (35 USC § 292) prohibits marking a product with a patent number that does not cover the product, with intent to deceive the public. The penalty is up to $500 per offense.
Pre-AIA (before 2011), false marking was aggressively litigated by qui tam plaintiffs — individuals who could sue on behalf of the government and collect half the fines. Thousands of suits were filed against companies that continued marking products with expired patent numbers. The AIA reformed this: now only the US government and parties who can show competitive injury can sue for false marking.
Common false marking mistakes to avoid: (1) continuing to mark after the patent expires (expired patent numbers are not false marking if done without deceptive intent, but update your markings anyway); (2) marking products with patents that don't actually cover those products; (3) listing patent numbers that have been found invalid; (4) failing to remove patents that have lapsed for non-payment of maintenance fees.
How to set up a virtual marking page
Create a publicly accessible webpage listing your patents and the products they cover. A simple table works: Patent Number | Product(s) Covered | Status. Include the word 'Patent' or 'Pat.' followed by the URL in your product marking.
The page must be freely accessible — no login, no paywall. It should be updated when new patents issue, patents expire, or a patent is found invalid. Keep a dated log of changes to the page (when patents were added or removed) — this can matter in litigation.
On your product: 'Pat.: [your-company.com/patents]' or 'Patent: [URL]' is sufficient. Place it where marking is normally displayed — on the product, on packaging, or in the user interface for software products.
For software and SaaS products: display the patent marking in the application's About screen, in the footer, or in a legally required notices file. The URL approach works well for software since products may be covered by dozens of patents and can't practically list all numbers.
Method-only patents: marking doesn't apply
Section 287's marking requirement applies only to patents that cover products (apparatus, composition, or device claims). It does NOT apply to method-only patents — patents whose claims cover only processes or methods, with no product claim.
If your patent covers only a method (e.g., a method of processing data), there is no product to mark, and § 287 does not require marking. You can still sue for infringement going back to when infringement began, without any marking requirement.
Most patent holders file both product and method claims in the same patent. For such mixed patents, § 287 applies — you must mark the product embodiment. Failure to mark forfeits pre-notice damages even if the infringement is of the method claims.