Can You Kill a Bad Patent? Reexamination, IPR, and Why Winning APEX Isn't Enough

Patent

Can You Kill a Bad Patent? Reexamination, IPR, and Why Winning APEX Isn't Enough

If the same weak patent keeps coming back at you, defending each complaint is treating symptoms. Here is what it takes to go after the patent itself — and when that math actually works.

By Kenneth G. Eade, CA Bar No. 93774, with Michael S. Brandt, USPTO Reg. No. 39119 · August 2, 2026

A pattern we see: a seller wins an APEX evaluation, feels relief, and four months later gets hit by the same patent owner on a different ASIN. Then again. Then a competitor in the same category calls with the same problem and the same patent number.

At that point the seller is no longer solving a listing problem. They are paying rent to a patent that may not have deserved to issue.

Infringement and validity are separate fights

This distinction governs everything else, and sellers collapse it constantly.

Infringement asks whether your product falls within the claims. That is the APEX question, and it is the question in most listing disputes.

Validity asks whether the patent should have issued at all — whether the claimed invention was already known or obvious in light of what came before.

Winning on infringement leaves the patent standing and available for the next assertion. Winning on validity removes it. That is why the two paths have such different costs and timelines: one resolves a dispute, the other removes a weapon.

The APEX evaluator cannot consider validity. Neither can Amazon. If the real problem is that the patent shouldn't exist, no marketplace process will ever fix it — that fight happens at the USPTO or in federal court.

Route one: ex parte reexamination

Anyone can ask the USPTO to reconsider an issued patent based on prior art — patents and printed publications — that raises a substantial new question of patentability. The Office decides whether that threshold is met and, if so, reexamines the claims.

The defining feature is in the name. It is ex parte: once instituted, the proceeding runs largely between the Office and the patent owner, and the requester steps back. That has two consequences sellers should weigh in opposite directions.

Cheaper and lower-profile. No discovery, no hearing, no sustained litigation posture. And in appropriate circumstances the requester need not be publicly identified — meaningful when you don't want to hand a patent owner your name and an infringement theory.

You lose control. You cannot respond when the patent owner argues around your art. And the patent owner can amend the claims during reexamination, which sometimes produces a narrower patent that survives — one that may or may not still read on your product. That is a real risk, not a footnote.

Route two: inter partes review

IPR is the contested proceeding before the Patent Trial and Appeal Board. You petition, you participate throughout, there is discovery and briefing and an oral hearing, and you argue your art rather than handing it over and hoping.

It is a genuinely powerful tool. It is also substantially more expensive, and it carries two features that make it the wrong instrument for most marketplace sellers.

Estoppel. A petitioner who receives a final written decision is barred from later raising grounds that were raised or reasonably could have been raised. Lose an IPR and you have narrowed your own defenses in any subsequent litigation. That is a serious commitment.

Timing bars. There is a window measured from service of an infringement complaint, and it closes. A seller who has been sued and waits may find the option gone entirely.

The prior art constraint nobody mentions

Both proceedings are limited to patents and printed publications. This is where seller cases most often fall apart, and it is worth understanding before you spend anything.

Sellers frequently know, with certainty, that the claimed invention was already being sold years before the patent was filed. Sometimes they were selling it. That knowledge is genuinely valuable — but it has to be documented to be usable here.

What works: dated catalogs, product manuals, archived web pages, dated marketplace listings, trade publications, technical articles, earlier patents and published applications, academic literature.

What doesn't, in these proceedings: the physical product on your shelf, your recollection, a supplier's word that they've made it for a decade.

So the first real question in any validity challenge is not "is this patent bad." It is "can we prove it was bad using documents that existed before the filing date." Those are different questions and only one of them is answerable by searching.

Choosing between them

Ex parte reexamination tends to fit where the art is strong enough to speak for itself, cost matters, anonymity is valuable, and you are not already in litigation.

IPR tends to fit where the stakes justify the spend, the art needs advocacy rather than just presentation, you are already litigating, and you can accept estoppel.

Neither fits where the art is thin, where the dispute is really about infringement rather than validity, or where the economics don't support it — which brings us to the honest part.

When it isn't worth it

For a single accused listing, a validity challenge is almost always the wrong tool. It costs more and takes longer than resolving the dispute on non-infringement, and the outcome is uncertain.

The math starts working when:

• The same patent has been asserted against you more than once
• It reads on a product category you sell in, not one item
• Multiple sellers are affected and can share the cost — this is more common and more workable than sellers assume
• The revenue at stake makes permanently removing the threat worth more than defending repeatedly
• The prior art is genuinely strong and genuinely documented

If none of those apply, defend the listing and move on. We will say so.

Frequently asked

What is ex parte reexamination?

A USPTO proceeding in which anyone may ask the Office to reconsider an issued patent based on prior art consisting of patents and printed publications, where the request raises a substantial new question of patentability. Once instituted it runs largely between the Office and the patent owner, with limited further participation by the requester — which makes it considerably cheaper than IPR and, in appropriate circumstances, allows the requester to remain unidentified.

What is inter partes review and how is it different?

A contested proceeding before the PTAB where the petitioner participates throughout, with discovery, briefing, and an oral hearing. Substantially more expensive than reexamination, and it carries statutory estoppel — a petitioner receiving a final written decision is barred from later raising grounds that were or reasonably could have been raised. There are also timing bars, including a window measured from service of an infringement complaint.

Can I challenge a patent anonymously?

Ex parte reexamination can in appropriate circumstances be requested without the challenger being publicly identified as the real party in interest — one reason sellers choose it when they don't want to invite an infringement suit. IPR requires identification of all real parties in interest and is not anonymous. Whether anonymity is available and advisable turns on the facts and should be assessed by patent counsel.

What kind of prior art can be used?

Both proceedings are limited to patents and printed publications. Evidence that a product was on the market before the patent was filed is powerful but generally has to be captured in a document — a catalog, manual, dated marketplace listing, archived web page, trade publication, or technical article. Physical products and personal recollection alone do not fit these proceedings, though they may be usable in litigation.

Is challenging a patent worth it for a single listing?

Usually not. It's expensive and slow relative to resolving one dispute, and the cheaper path for a single accused product is normally a non-infringement position in the Amazon evaluation. It starts making sense when the same patent is asserted repeatedly, when it covers a category rather than one item, when multiple affected sellers can share cost, or when the revenue at stake makes permanently removing the threat worth more than defending repeatedly.

Send us the patent number.

Our USPTO-registered patent attorney will assess whether documented prior art exists, which route the facts support, and whether the economics justify going after the patent instead of the complaint.

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General information only, not legal advice, and no attorney-client relationship is created by this post. Availability of particular proceedings, timing bars, estoppel consequences, and USPTO fees depend on the specific facts and are subject to change. Attorney advertising. Related: APEX defense · patent services · IP litigation