If you believe someone is infringing your patent, the correct order of operations is: confirm the infringement claim-by-claim before saying anything publicly, gather and preserve evidence of the copy before the seller can change it, and then escalate through the cheapest effective remedy first — usually a marketplace takedown or a carefully drafted letter from counsel — reserving litigation for the cases where the commercial damage justifies it. A patent is not self-enforcing. No agency scans the market on your behalf, and how you handle the first move largely determines whether your investment in protection produces a result or stays a piece of paper.

Step One: Confirm There Is Actually Infringement

Before any action, do the cold analysis. In the US, direct infringement of a claim requires that the accused product contain every element of that claim. General similarity is not enough, and neither is the accused product doing the same job by a different mechanism. The comparison is made against the granted claim language, ideally with a patent attorney, and it produces a document: a claim chart, element against element, with photographs or measurements as evidence for each row.

Two things get checked alongside it. First, is the patent in force in the country where the sales are occurring? A US patent does not stop sales in Germany. Second, is the patent in good standing — maintenance fees paid, term not expired? Reading the document correctly matters here, and our guide to how to read a patent covers the difference between what the description says and what the claims actually cover. If your rights are still pending rather than granted, your options are narrower than most inventors assume — see what patent pending means.

Step Two: Gather Evidence Before You Reach Out

The moment an infringer receives a communication, they may change the product, pull the listing, or move inventory. So document first:

  • A documented purchase of the accused product with an invoice, shipping record, and unopened packaging retained.
  • Dated screenshots or archived captures of the sales pages, marketing claims, and any technical specifications.
  • A photographed teardown showing each infringing element, cross-referenced to your claim chart.
  • Whatever you can establish about scale — how long it has been sold, in what channels, and roughly at what volume.

This record is the foundation for every subsequent step, and it is far harder to reconstruct later.

Step Three: The Ladder of Responses

Marketplace takedowns

When the copy is sold on an online platform, the platform's own IP reporting process is dramatically faster and cheaper than any legal proceeding. Major marketplaces will remove listings on the basis of a patent — utility or design — often within days, though their programs generally require a registered right and, for utility patents, sometimes a more involved evaluation. Design patents in particular are effective here because infringement is visually obvious. If you sell through those channels yourself, being enrolled in their brand and IP programs before you need them is worth doing early, as noted in selling a product on Amazon FBA. See also utility patent vs design patent for why the design right often does the heavy lifting.

A demand letter

A letter from counsel presenting the patent and the comparison, and demanding that the activity stop. A meaningful share of cases end here — particularly with distributors, importers, and retailers, who have no appetite for trouble over one product line. This letter must be drafted by an attorney. A poorly worded threat can expose you to a declaratory judgment action filed in a forum of the other side's choosing, or to liability for improper threats. Do not send it yourself, and do not send it before step one is complete.

Negotiating a license

Sometimes the best outcome is not stopping the sales but getting paid for them. An infringer who is already manufacturing, distributing, and selling can be more valuable as a royalty payer than as a removed competitor. The economics are the same as any licensing deal — see invention royalty rates and licensing vs manufacturing.

Customs recordation and border enforcement

For imported goods, recording rights and working with border enforcement can stop shipments before they reach distribution. This is more established for trademarks and copyrights than for utility patents, but it is worth discussing with counsel where imports are the channel.

Litigation

The last step, not the first. US patent litigation runs for years and costs large sums, and it should be weighed only when the commercial harm justifies the expense and the patent is strong enough to survive attack.

The Risk You Must Understand: They Will Attack the Patent

An accused infringer who is sued will almost always counterpunch by challenging the patent's validity — in court, or through a post-grant proceeding at the USPTO. If prior art the examiner missed turns up, the claims can be narrowed or cancelled entirely, and you finish the fight having lost the protection you started with. So before opening any proceeding, stress-test your own patent with critical eyes: a fresh prior art search against your claims, exactly the discipline described in prior art search and, from the other direction, freedom to operate search. It is also worth confirming your own product does not infringe someone else's patent, because that is a favorite countermeasure.

Choose Your Battles

Not every infringement is worth a war. A marginal seller moving a few dozen units a year does not justify a proceeding costing six figures; a takedown and a letter are the proportionate response. Save the serious fight for whoever is genuinely eating your market: an established competitor, a large importer, or an infringer whose presence is blocking a licensing deal you want to close. Organized companies treat this as a budget line — a defined annual amount for monitoring and enforcement, a priority order based on commercial damage, and cold decisions instead of emotional reactions. Patent enforcement insurance exists and can cover part of the cost of proceedings, which is worth exploring if you know in advance that your market is crowded with well-funded players. And a reassuring reality: the overwhelming majority of patent disputes end in settlement or a license rather than a judgment.

Do Not Sleep on It

Time works against a rights holder who knew about infringement and stayed silent for years — delay can limit the remedies available and signals acquiescence. So even when you decide not to act legally, document the decision and its reasoning, and at minimum put the other party on notice that the patent exists. Marking your own product properly also matters, since it affects what damages you can recover.

Good Enforcement Starts at Drafting

How easy your patent is to enforce is largely determined years earlier, when the application is written: claims aimed at what is visible and detectable in a shipped product, filing in the countries where the market actually is, and orderly records of conception and development. That preparation is covered in how to patent an idea, and choosing the right professional to do it in patent attorney vs patent agent. More across our patents and intellectual property hub.

Projects House is an engineering firm, not a law firm. This article is educational only and is not legal advice; consult a licensed patent attorney about your specific situation.

The Engineering Side of an Enforcement Case

Confirming infringement is partly a technical exercise: a teardown, measurements, and a documented element-by-element comparison an attorney can build on. Projects House does that engineering analysis, and we also help clients redesign around a competitor's move or strengthen the next generation. Facing a copy of your product? Describe the situation through the contact form.