Patent Marking, Virtual Marking, and the Damages Consequence

Patent marking is the least glamorous item in a patent portfolio's maintenance list and one of the most expensive to get wrong. Under 35 U.S.C. § 287(a), a patentee who makes or sells a patented article and fails to mark it cannot recover damages for infringement that happened before the infringer received actual notice. Years of infringement can simply drop out of the case.

The rule exists to give the public notice of patent rights. Its practical effect is to convert a labelling decision into a damages decision — one that has to be made when products launch, not when litigation starts.

What the statute requires

Notice can be given two ways. Constructive notice comes from marking: fixing on the article the word "Patent" or the abbreviation "Pat." together with the patent number, or, where the article's character makes that impractical, applying the marking to the package. Actual notice comes from an affirmative communication from the patentee to a specific accused infringer, identifying the patent and charging a specific product with infringement.

Since the America Invents Act took effect in 2011, a third option exists. Virtual marking allows the word "Patent" or "Pat." together with an internet address of a freely accessible posting that associates the patented article with the patent number. That change removed the practical objection that physical marking becomes obsolete every time a patent issues or expires.

Two limits are worth stating plainly. Marking is not mandatory — nothing requires a patentee to mark. It is a precondition to a category of damages, so a patentee who never marks still has a valid patent, an injunction claim, and damages from the date of actual notice forward. And marking has to be substantially consistent and continuous once begun; sporadic marking of some units does not create constructive notice for the rest.

Products, methods, and the mixed patent

The marking duty attaches to tangible articles. Where a patent contains only method claims, there is nothing to mark and the requirement does not apply — a rule that has been settled for a long time and that materially advantages process-heavy portfolios.

The complications arise with patents that claim both an apparatus and a method. Where the patentee sells a product that practises the apparatus claim and asserts that claim in litigation, the marking duty applies to that product. A patentee asserting only the method claims from such a patent generally avoids the bar, which creates a real litigation choice: dropping apparatus claims can recover years of damages, at the cost of the infringement theories those claims supported.

Software and services complicate the analysis further. Whether a downloaded application, an embedded module, or a hosted service is an "article" that can be marked is fact-specific and has been litigated with mixed outcomes. The conservative practice is to mark anyway — in the interface, in the documentation, and on the virtual marking page — because the cost of marking is trivial next to the cost of arguing about it.

Deadline discipline: the marking rule and the six-year limitation in the Patent Act are separate. Marking decides when damages start; the six-year rule caps how far back recovery can reach from the date of the complaint. A patentee can satisfy one and still lose years to the other.

Virtual marking done properly

• Mark the article itself with "Pat." and a stable URL. A page reachable only through a login, a site search, or a redirect chain undermines the statutory purpose.
• Put the association on the page, not just a list of patents. The statute contemplates a posting that associates the patented article with the number, so pair product identifiers with patent numbers.
• Cover product variants, model numbers, and regional versions explicitly. A generic corporate patent list does not tell anyone which patent covers which product.
• Keep the page free of charge and accessible to the public, without registration or acceptance of terms.
• Archive every version with a date. If marking is challenged years later, you will need to prove what the page said and when.
• Diary a review whenever a patent issues, expires, is cancelled, or a product changes. Stale pages create both under-marking and false-marking exposure.
• Assign an owner. Marking usually fails because it belongs to nobody — not because anyone decided against it.

Physical marking still has a place. Where a product is sold in channels the buyer will never associate with a website, or where a licensee's packaging is already being reprinted, the direct mark is simpler. Many portfolios use both: the article carries "Pat." plus the URL, and high-value flagship products carry the numbers as well.

Licensees and the reasonable-efforts duty

The most common way a marking programme fails is through someone else's products. Where a patentee licenses others to make or sell covered articles, those licensees' unmarked sales can defeat constructive notice just as the patentee's own would. The Federal Circuit has required patentees to make reasonable efforts to ensure licensee compliance, and has held that stopping the unmarked sales does not retroactively cure the earlier failure — the patentee is limited to actual notice from that point.

The fix is contractual and should be in every licence that permits manufacture or sale.

1. Require marking expressly

   Obligate the licensee to mark all covered products in the manner the patentee specifies, including the virtual marking URL, and to update within a stated period after notification of a change.

2. Identify covered products

   Maintain a schedule that lists which licensee products are covered by which patents, updated as the product line changes. This is the document that proves compliance later.

3. Build in verification

   Add sample and audit rights, and use them. An exclusive license for an entire field makes the licensee's practice the patentee's whole marking record.

4. Attach a consequence

   Make failure to mark a curable breach with a stated cure period, and consider an indemnification for damages lost through non-compliance.

5. Keep evidence

   Photographs, packaging samples, dated screenshots, and correspondence about compliance. The alleged infringer bears an initial burden of identifying unmarked products, after which the patentee must prove compliance.

Licences granted for settlement purposes deserve the same treatment. A patent asserted against ten defendants and settled with covenants and licences can quietly create ten sources of unmarked product. The broader drafting framework sits in licence scope, exclusivity, and royalties.

Actual notice as the fallback

1. Before any notice

   Where marking has failed, no damages accrue for this period, regardless of how long or how extensive the infringement was.

2. The notice communication

   Actual notice requires an affirmative act by the patentee: identification of the patent and a specific charge of infringement against a specific accused product or activity. The infringer's independent knowledge of the patent does not count.

3. From that date forward

   Damages accrue. Willfulness analysis also begins to have something to work with, since knowledge of the patent is a precondition to enhanced damages.

4. Filing the complaint

   Service of a complaint alleging infringement gives notice as a matter of law, so a patentee that never sent a letter still recovers from the filing date. Note that service also starts the one-year clock in 35 U.S.C. § 315(b) for the defendant's own inter partes review petition.

5. Six years before filing

   Independently of notice, recovery reaches no further back than six years before the complaint or counterclaim was filed.

Because the notice letter is doing damages work, its content is not a formality — and the same letter carries declaratory judgment risk, which is why the drafting choices in cease-and-desist strategy should be made with the marking position in mind. A patentee with clean marking has less reason to send a specific, jurisdiction-creating letter, because damages are already running.

Marking too much: false marking

Over-marking has its own statute. Marking an unpatented article with a patent number, or with "patent pending" when no application is pending, for the purpose of deceiving the public, is prohibited. The America Invents Act reshaped the remedy: only the United States may sue for the statutory penalty, and a private party may bring a civil action only if it has suffered a competitive injury, recovering damages adequate to compensate for that injury rather than a per-article penalty. The same legislation confirmed that marking a product with a patent that once covered it but has since expired is not a violation.

That reform removed the wave of bounty-style litigation that preceded it, but it did not make over-marking safe. Competitive-injury suits remain available, deceptive marking can feed unfair competition and false advertising theories under the standards described in advertising substantiation and Lanham Act exposure, and a marking page listing patents that plainly do not cover the listed products damages credibility in any enforcement action.

Questions the desk gets

We have never marked anything. Should we start now?

Yes, and immediately. Marking is prospective: constructive notice begins when consistent marking begins, so every week of delay is a week of damages you cannot recover from an infringer you have not yet identified. Starting now does not repair the past, but it fixes the future, and the cost is a page on your website plus a change to packaging artwork.

Can we list all our patents on one page and call it virtual marking?

That is the most common defective implementation. The statute contemplates a posting that associates the patented article with the patent number, which means product-to-patent mapping rather than a portfolio list. Build a table keyed to product identifiers, keep discontinued products listed with their dates, and archive versions so you can prove what was published when.

Does marking affect willfulness or enhanced damages?

Indirectly. Enhanced damages depend on the infringer's knowledge and conduct, and a marked product supports an argument that the infringer had access to notice of the patent. It is not a substitute for evidence that the infringer actually knew and proceeded regardless, which is what a documented notice letter and the response to it provide.

Our patent was challenged at the PTAB. Does that change marking practice?

Not while the claims stand. If claims are cancelled and the patent no longer covers the marked product, update the marking page promptly, because continuing to list a cancelled patent against a product invites a false-marking argument and undermines your enforcement record. Diary the review to the date any final written decision issues rather than waiting for appeals.

Where the risk actually sits

The risk sits in the gap between the portfolio and the product line. Someone has to know which products practise which claims, and that mapping has to be maintained as products change and patents issue and expire. Portfolios fail marking not because the rule is hard but because nobody owns the table.

Build that table first, then implement virtual marking against it, then push the same obligation into every licence with a verification mechanism you will actually use. Review it on a fixed schedule and archive each version. When enforcement eventually starts, the marking record decides whether the case is about six years of damages or six months of them. Related patent, licensing, and enforcement work sits on the Intellectual Property & Media desk. This brief is general information about federal patent law, not legal advice about a specific product or portfolio.