Two precedential decisions call post-grant review petitions favored. A post-grant review filed on the last day of its window was referred despite an earlier trial date, and went to trial. An inter partes review that leaned on the same principle cleared the Director, then was denied by the Board 59 days later.
Before you read
What share of FY2026 PTAB petitions were PGRs?
About 10%: 48 of 500 petitions. The rest were IPRs.
Part 1 of 7
Brook & Whittle’s patent issued on April 16, 2024. Multi-Color filed its post-grant review petition on January 16, 2025, the day the nine-month window closed. A Texas trial on the patent was set before the PGR’s final-decision date, a fact that weighs toward denial. The Director referred the petition anyway, and the Board instituted trial on September 19, 2025.
Source
Part 2 of 7
A post-grant review is the PTAB’s broadest validity challenge. An IPR is limited to anticipation and obviousness based on patents and printed publications. A PGR can raise any invalidity ground under 35 U.S.C. § 282(b)(2) or (3), including eligibility and written description. The catch is timing: the petition must be filed within nine months of grant.
| IPR | PGR | |
|---|---|---|
| Grounds | Anticipation and obviousness over patents and printed publications | Any ground under § 282(b)(2) or (3) |
| When | After the PGR window | Within nine months of grant |
| Estoppel after a final decision | Grounds raised or reasonably could have raised | The same, across the wider set of grounds |
35 U.S.C. §§ 311(b), 315(e), 321(b)–(c), 325(e).
PGRs are a small share of the docket.
500 petitions, Oct 1, 2025 to Sep 30, 2026
Tap a segment to read what it covers.
Source
Part 3 of 7
Both decisions use the same sentence.
“[Petitions for post-grant review] are favored because they must be filed no later than nine months from the grant of the patent (35 U.S.C. § 321(c)), are close in time to examination, and occur before expectations in the patent rights are strongly settled.”
The reasoning ties into settled expectations. A PGR, by definition, comes before anyone has had years to build on the patent.
Part 4 of 7
Multi-Color’s facts pointed both ways, and the decision says so.
The patent was in two court cases. The Texas trial was set about four months before the September 21, 2026 final-decision date.
Multi-Color wasn’t a party to either case and said it had no substantive relationship with any defendant. The Delaware case had no trial date. And the petition was filed within nine months of grant.
The Director found the factors against denial outweighed those for it and referred the petition on July 16, 2025. The Board instituted trial 65 days later.
Part 5 of 7
LifeVac shows the limit. LifeVac had challenged the same patent in a PGR, and the Board denied institution on the merits on November 29, 2023. When LifeVac came back with an IPR, the owner argued it was a repeat attack.
The Director disagreed with the owner. The earlier challenge “did not result in a final written decision,” and because PGRs are favored, “petitions for inter partes review will generally not be discretionarily denied because of an earlier petition for post-grant review when the post-grant review was not instituted.”
Fifty-nine days later, the Board denied institution. The Board’s reasons have not been read. The favored status got LifeVac past discretionary review. It didn’t decide the merits.
Part 6 of 7
Choose your side.
Part 7 of 7
Both decisions are precedential, so the favored framing binds the Board at the discretionary stage. It says nothing about the merits, and two decisions are a thin base.
It does
It doesn’t
The wider grounds also widen the risk. After a PGR final written decision, the petitioner may not pursue before the Office any ground it “raised or reasonably could have raised during that post-grant review.”
The takeaway
Calendar the nine-month window at issuance. The edge it buys is real, and it ends at the merits.
Each item is marked in the story with a dashed outline. We update the story when the official record confirms or corrects it.
Precedential decisions bind the Board within their designated scope. Informative decisions show the Office’s reasoning but do not bind the Board. Court opinions are cited for what they decided; later history was checked on the date shown above.