Summary. Patent marking under 35 U.S.C. § 287 is one of the most consequential yet most overlooked compliance obligations in patent law—failing to mark can erase years of pre-suit damages even against a deliberate copyist, and after SCA Hygiene abolished laches, marking is now the single most important limit on how far back a patentee can reach for damages. This checklist walks a patentee through earning constructive notice by consistent, continuous marking; using the AIA virtual-marking website option; policing licensees (with the Arctic Cat burden-shifting framework); handling method claims and multi-patent products; sending an effective actual-notice letter while managing declaratory-judgment risk; and avoiding false-marking liability under § 292. It closes with an auditable compliance program. Verify current fees and any deadlines at the official site.

Few obligations in patent law are as cheap to satisfy and as financially devastating to neglect as patent marking. A company can prosecute a patent for half a million dollars, sell the covered product for years without ever stamping a patent number on it, and then discover in court that the law forbids recovery of a single dollar for those years—even against an infringer who copied on purpose. The cure cost a few cents per unit; the omission can cost millions. And since SCA Hygiene Products Aktiebolag v. First Quality Baby Products, LLC, 580 U.S. 328 (2017), abolished laches as a defense to damages within the six-year window of § 286, 35 U.S.C. § 287 is now the principal doctrine determining how far back a patentee can reach.

Marking is not a condition of validity—an unmarked patentee can still sue and win on liability. What marking governs is the timing of damages. The whole doctrine is about notice. For depth, pair this checklist with understanding patent marking requirements: a practical guide for practitioners and entrepreneurs and the broader understanding patent and trade dress marking requirements.

Phase 1 — Determine whether the marking duty applies

  • Confirm there is a tangible patented article you (or a licensee) make, offer for sale, sell, or import—§ 287 attaches to articles.
  • Check whether the patent has only method/process claims—a method patent covers no physical product to stamp and is generally not subject to the marking requirement.
  • If you are a non-producing patentee who neither makes nor licenses the manufacture of any article, note that you may recover full damages without marking (Wine Railway Appliance Co. v. Enterprise Railway Equipment Co., 297 U.S. 387 (1936))—but the duty reattaches the moment you or a licensee sells a covered product.
  • For a product covered by multiple patents, plan to mark all applicable patents (virtual marking, below, makes this manageable).

Phase 2 — Earn constructive notice by marking correctly

  • Mark the article with the word "patent" or "pat." together with the patent number—a bare "Patented" or "Patent Pending" without a number does not satisfy § 287.
  • Prefer marking the article itself; mark the package only where the article cannot practicably bear the mark (too small, would be defaced).
  • Make the mark visible and durable (Arcadia Machine & Tool, Inc. v. Sturm, Ruger & Co., 786 F.2d 1124 (Fed. Cir. 1986)).
  • Mark substantially consistently and continuously—once marking begins, gaps or sporadic marking forfeit constructive notice for the unmarked stretches (Nike, Inc. v. Wal-Mart Stores, Inc., 138 F.3d 1437 (Fed. Cir. 1998)).
  • Mark from the first sale so constructive notice is in place and the actual-notice inquiry never matters.

Why this matters. Constructive notice is the prize: it decouples damages from the infringer's state of mind and lets you recover for infringement throughout the six-year § 286 window, regardless of when the infringer learned of the patent—and, after SCA Hygiene, without equitable shortening for delay. Note: the patentee bears the burden of proving compliance (Maxwell v. J. Baker, Inc., 86 F.3d 1098 (Fed. Cir. 1996)).

Phase 3 — Use the AIA virtual-marking option (optional, recommended for portfolios)

  • Mark the article with "patent" or "pat." plus an internet address of a publicly accessible page (e.g., "Patented. See www.example.com/patents").
  • Maintain a web page that associates each patented article with its patent number(s) and keeps the list current as patents issue or expire.
  • Keep the URL stable and the page freely accessible (no login).
  • Archive prior versions of the page so you can prove what the page said on any given date.

Virtual marking solves the burden of re-tooling molds and labels every time a patent issues or expires—the web page does the work the product surface once had to.

Phase 4 — Police your licensees

  • Include a marking obligation in every license that authorizes a licensee to make or sell covered articles.
  • Monitor and enforce licensee compliance—an unmarked licensee product can defeat your constructive notice.
  • Understand the burden-shifting framework: an accused infringer must first identify unmarked products it alleges were covered (a low bar of production), after which the patentee bears the burden of proving the products were marked or not covered (Arctic Cat Inc. v. Bombardier Recreational Products, Inc., 876 F.3d 1350 (Fed. Cir. 2017)).
  • Keep records sufficient to carry that burden across the entire licensee population.

Phase 5 — When you did not mark: give effective actual notice

Phase 6 — Manage the notice-letter / declaratory-judgment tension

Phase 7 — Avoid false marking

  • Do not mark an unpatented article as patented (or use "patent pending" with no pending application) with intent to deceive the public (35 U.S.C. § 292).
  • Promptly remove or update markings for patents that have expired or been held invalid.
  • Note post-AIA false-marking liability is largely limited to a competitor who suffered a competitive injury; the broad qui tam bounty regime is gone.

Phase 8 — Build an auditable compliance program

  • Maintain a master list mapping each product (and SKU) to the patents that cover it, reviewed by counsel.
  • Assign ownership: who updates the virtual-marking page, who audits physical marking, who tracks licensee compliance.
  • Calendar maintenance-fee and expiration dates so markings come off when patents lapse.
  • Retain dated evidence of marking (product photos, label specs, web-page archives, licensee certifications) to meet the patentee's burden of proof.
  • Re-audit on a schedule and on every product change, new patent issuance, or new license.

Common mistakes

  • No number ("Patented" or "Patent Pending" alone is insufficient).
  • Inconsistent or interrupted marking (sporadic marking is, for damages, close to no marking).
  • Ignoring licensees (an unmarked licensee product destroys your constructive notice).
  • A "friendly license" letter that names the patent but accuses no specific product—it does not start the damages clock.
  • Leaving stale markings on expired patents, inviting false-marking exposure.

Primary authority

This checklist is general information, not legal advice. Consult qualified patent counsel about your products and licenses.

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