The envelope nobody plans for

A patent cease and desist letter almost always arrives at the worst possible moment: after the product is in production, days before a trade show, or the week a large purchase order ships. It is written in aggressive language, demands that you stop making and selling immediately, and often asks for sales figures and damages on top. The natural reaction is panic. The correct reaction is process. This article explains what the document actually is, what to do in the first week, and which options are realistically on the table.

This is general educational information from an engineering firm, not legal advice. Projects House is a product development company, not a law firm. Any letter of this kind should go to a patent attorney before you respond to it. What we can help with is the engineering side — understanding the claimed technology and evaluating whether and how a product can be changed.

What the letter is — and what it is not

  • It is not a judgment. It is one party's position, written to produce a result. No court has decided that you infringe anything.
  • It is often an opening move in a negotiation. A large share of these letters are aimed at a royalty-bearing license rather than a lawsuit, because litigation is expensive for the sender too.
  • Sometimes it is a form letter. Some patent owners and non-practicing entities send near-identical letters to dozens of companies in a sector without examining any individual product closely.
  • And sometimes it is extremely serious. When the sender is a direct competitor with a strong patent and in-house counsel, ignoring it can be catastrophic. The safe assumption is that every letter is serious until proven otherwise.

Five mistakes people make in the first week

  • Replying immediately, in writing. Anything you write can be used later. Do not correspond before you have advice.
  • Calling to explain. A friendly conversation "to clear things up" hands the other side technical detail they did not have.
  • Deleting or altering documents. Preserve everything — development logs, emails, CAD revisions, supplier correspondence. Destruction of records looks far worse than the underlying dispute, and a hold on deletion should go out to the team the same day.
  • Total silence for months. Prolonged non-response can be characterized as willful continuation and raise your exposure.
  • Panic-stopping everything. Halting production instantly damages you financially before anyone has established that infringement exists.

What to verify before you respond

The review runs in a fixed order, and at any step the matter may quietly resolve itself.

  • Is the patent still in force? US patents lapse at the end of their term, and earlier if maintenance fees were not paid at the required intervals. This is the cheapest, fastest check available, and it closes a surprising number of letters — see how long a patent lasts and the practical lookup habits in searching expired patents.
  • Which territory does it cover? Patents are national. A US patent bars making, using, selling, offering for sale, and importing within the United States — it says nothing about what you manufacture and sell elsewhere, and a foreign patent says nothing about your US sales.
  • Is it a granted patent or a pending application? A published application confers no enforceable right yet, though it signals what may be coming.
  • What do the claims actually say? Protection lives in the claims alone, not in the description, the drawings, or the abstract. The comparison is element by element against an independent claim: if your product lacks even one element of that claim, it does not literally infringe it. Read patent claims explained before you form an opinion about the letter.

The options on the table

After that review, one of several paths usually stands out. The first is a reasoned non-infringement response showing the product falls outside the claims, which frequently ends the matter. The second is a validity challenge, when prior art exists that predates the patent's priority date — through prosecution history, reexamination, or a post-grant proceeding, all of which are counsel's territory. The third is an engineering change that moves the product clear of the claims, discussed on its own in designing around a patent. The fourth is a royalty-bearing license, which is sometimes the cheapest and fastest outcome available. The fifth is a broader commercial arrangement, up to acquiring the rights. The mirror-image situation — you own the patent and someone else is copying you — is covered in what to do about patent infringement.

What to actually do, in order

Scan the letter and record the date it arrived. Circulate a document-preservation notice internally. Gather the development record showing when and how you arrived at your solution. Engage a patent attorney — the differences between practitioner types are in patent attorney vs patent agent — and give them the patent number and your product file. Respond only after you have an opinion.

In parallel, prepare. Price what a design change would cost, count the inventory and tooling already committed, and check your contractual exposure to customers and distributors, including indemnity clauses. Check whether your business insurance covers intellectual property defense costs. Brief your board or investors in real time rather than after the fact. That preparation is where negotiating leverage comes from: a company that knows exactly what a redesign costs holds a very different conversation from a company that is only frightened.

Most of these matters end in a settlement, a license, or a targeted engineering change — not in a courtroom. More background is collected in our patents and intellectual property hub.

Need the engineering side evaluated — whether your product can be changed to fall outside a claim, and what that would cost? Projects House can review the technical comparison and scope the redesign alongside your attorney. Contact us through the form to discuss it.