Inter partes review: what a PTAB history tells you
How inter partes review works (grounds, deadlines, burden of proof, estoppel) and how to read a patent's PTAB history before licensing, suing or buying.
By the One Transform team7 min read
Inter partes review (IPR) is a trial before the USPTO's Patent Trial and Appeal Board (PTAB) in which anyone other than the patent owner can ask for claims to be cancelled as anticipated or obvious over patents and printed publications. Because the record is public and claim-specific, a patent's PTAB history is one of the most useful things to read before licensing, asserting or buying it. It shows who has challenged the patent, with which art, and which claims came through.
The first part of this post covers how IPR works. The second covers how to read a patent's PTAB record and use it.
How inter partes review works
Who can file, and on what grounds
Under 35 U.S.C. § 311(a), any person who is not the owner of the patent may file a petition. Section 311(b) limits the grounds to §§ 102 and 103, and limits the prior art to patents and printed publications.
That leaves out two things a district court can consider: invalidity under § 101 or § 112, and prior art in the form of public uses or sales. Petitioners usually support their grounds with an expert declaration, but the art itself must be patents or printed publications. For how the two available grounds differ, see Anticipation vs. obviousness.
When a petition can be filed
| Limit | Rule | Source |
|---|---|---|
| Earliest | For patents under the first-inventor-to-file rules, not before the later of 9 months after grant or the end of any post-grant review; older patents can be challenged at any time after grant | § 311(c); 37 C.F.R. § 42.102(a) |
| Latest, once sued | Time-barred if filed more than one year after the petitioner, its real party in interest or a privy was served with a complaint alleging infringement of the patent | 35 U.S.C. § 315(b) |
Institution
The Board first decides whether to institute a trial. Under 35 U.S.C. § 314(a), it may do so only if there is a reasonable likelihood that the petitioner would prevail on at least one challenged claim. In SAS Institute Inc. v. Iancu, 138 S. Ct. 1348 (2018), the Supreme Court held that when the Board institutes review, it must decide the patentability of every claim the petitioner challenged.
Institution is also discretionary. In Apple Inc. v. Fintiv, Inc., IPR2020-00019 (PTAB Mar. 20, 2020) (precedential), the Board set out factors for denying institution when parallel district court litigation is advanced. USPTO practice on discretionary denial has changed several times since then, so check the current USPTO guidance before relying on any particular approach.
Claim construction and burden of proof
For petitions filed on or after November 13, 2018, 37 C.F.R. § 42.100(b) requires the Board to construe claims under the same standard used in civil actions, the Phillips standard. Earlier petitions were decided under the broadest reasonable interpretation. The difference is covered in Claim construction: Phillips vs. BRI.
Under 35 U.S.C. § 316(e), the petitioner bears the burden of proving unpatentability by a preponderance of the evidence. That is a lower bar than a challenger faces when arguing invalidity in court.
Decision, Director Review and appeal
Under § 316(a)(11), the Board issues a final written decision within one year of institution, extendable by up to six months for good cause. In United States v. Arthrex, Inc., 594 U.S. 1 (2021), the Supreme Court held that final decisions of administrative patent judges must be reviewable by the USPTO Director, which led to the Director Review process. A party dissatisfied with the final written decision may appeal to the Federal Circuit under § 319.
Estoppel
Under § 315(e), when an IPR results in a final written decision on a claim, the petitioner, its real party in interest and its privies may not later raise against that claim any ground they raised or reasonably could have raised during the review. The estoppel applies in later USPTO proceedings and in civil actions and International Trade Commission proceedings. It attaches through a final written decision, so a petition that is denied, or settled before a decision, does not create it.
Post-grant review in brief
Post-grant review (PGR) is the broader, earlier option. Under 35 U.S.C. § 321, a PGR petition must be filed within 9 months of grant, can raise any ground of invalidity, and is available for patents governed by the America Invents Act's first-inventor-to-file rules. Because the window is short, most challenges to patents older than nine months run through IPR.
| IPR | PGR | |
|---|---|---|
| Filing window | After the PGR window for first-inventor-to-file patents, any time after grant for older ones; one-year bar after a complaint | Within 9 months of grant |
| Grounds | §§ 102 and 103 only | Any ground of invalidity |
| Prior art | Patents and printed publications | Not limited to those |
| Patents covered | Any issued patent | First-inventor-to-file patents |
What a PTAB history tells you
PTAB trial records are public and can be searched by patent number. For a patent you are evaluating, collect every petition filed against it and read for five things.
1. How each petition ended
| Outcome | What it tells you |
|---|---|
| Denied on the merits | The Board saw no reasonable likelihood of success on any challenged claim with that art. A preliminary view on those grounds only, and silent on other art. |
| Denied on discretionary grounds | Nothing about the strength of the art. The same references may reappear in court. |
| Instituted, then settled | The Board saw a reasonable likelihood of success on at least one claim. No final written decision, so no § 315(e) estoppel. A settlement often points to a license or other deal between the parties. |
| Final written decision | A claim-by-claim result on every challenged claim. Check for Director Review and appeal before treating it as final. |
2. Which claims survived
A final written decision identifies which challenged claims were shown unpatentable and which were not. Claims that were never challenged were never tested. A claim that came through a final written decision has survived a challenge under the preponderance standard (and, for petitions filed since November 2018, under the court's claim construction standard). Practitioners generally give it more weight than a claim that has only been through examination.
3. Which art has already been tested
The petition, the institution decision and the final written decision list the references and combinations argued, and the Board's reasons for accepting or rejecting them. New invalidity work should start there. Repeating art the Board already rejected wastes effort, while references cited in the record but never pressed may still be worth a look. The Board's construction of disputed terms is also a useful early reading of the claims.
4. Who is estopped, and who is time-barred
Estoppel under § 315(e) binds the petitioner, its real party in interest and its privies; other challengers are not bound. The § 315(b) bar is also party-specific, because it runs from service of a complaint on that party. Map both against the companies you care about: a prospective licensee, a defendant, a buyer's competitors.
5. Whether the claims changed
A patent owner can move to amend claims during an IPR. Substitute claims differ from the claims as issued, and a claim chart built on the original wording may no longer match the patent. Once the proceeding is final, the USPTO issues a certificate reflecting the cancelled, confirmed and new claims, so read the claims as they stand after it.
Using the history in practice
Licensing
For a licensor, a final written decision upholding the claims in suit answers the licensee's first validity argument with a record. For a licensee, a pending or instituted petition strengthens the negotiating position. If the licensee was itself a petitioner, check which grounds it may now be estopped from raising.
Assertion
Before asserting, list the potential defendants and check the history against each one. A defendant has one year from service of the complaint to petition under § 315(b), and the Board's approach to discretionary denial when litigation is advanced can affect whether that petition is instituted. Claims that survived a final written decision over the strongest known art are usually the safer ones to lead with.
Acquisition
A buyer should read the PTAB history before the price is set, alongside the patent's expiry date, maintenance status and chain of title. Pending petitions are a direct risk to the asset, and a recent institution decision can change its value quickly. Settled petitions may point to licenses the seller should disclose.
Pairing the PTAB record with a new search
A PTAB record shows what art has been tested. It does not show the art that nobody has argued yet. One Transform's Validity search examines a patent the way an opposing party would: it builds a prior-art record and analyzes anticipation, obviousness, definiteness and enablement, eligibility, prosecution history and double-patenting exposure. It scores each claim on a 0–10 scale and cites the references and reasoning behind each conclusion.
Read its results next to the PTAB file. References the Board has already considered need less attention than ones it has not seen.
Next step
Before your next license, assertion or acquisition, pull the patent's PTAB file and run a Validity search on the same claims at onetransform.ai.
This article is general information about patent practice, not legal advice. For advice on a specific matter, consult a registered patent attorney or agent.
