An IPR prior art search looks for patents and printed publications that can support a petition for inter partes review (IPR) at the Patent Trial and Appeal Board (PTAB). A search for post-grant review (PGR) is similar but accepts wider evidence. Both differ from a general patent invalidity search because the statute limits what a petition can rely on and when it can be filed.
An IPR can cancel a claim only for lack of novelty or obviousness, and only on the basis of patents or printed publications (35 U.S.C. 311). The wider process is covered in the patent invalidity search guide.
What the search must find
For each challenged claim, the petition must name the ground and the documents relied on, and show where each claim element is found in them. A reference that discloses most of a claim is useful only if another reference supplies the missing element and there is a reason to combine them.
The search is therefore built around the elements of the independent claims, with the best passages and figures recorded for each one.
IPR prior art search vs PGR search
PGR covers only patents under the first-inventor-to-file rules of the America Invents Act (AIA), broadly those with a claim whose effective filing date is on or after 16 March 2013.
| Point | IPR | PGR |
|---|---|---|
| Grounds | Novelty and obviousness only | Any invalidity ground, including eligibility, written description, enablement and indefiniteness |
| Evidence | Patents and printed publications | Also public use, sales and other disclosures |
| Filing window | AIA patents: 9 months after grant or after an instituted PGR ends; older patents: from grant | Within 9 months of grant |
| Official fees, up to 20 claims | USD 23,750 request, USD 28,125 post-institution | USD 25,000 request, USD 34,375 post-institution |
Fees are from the fee schedule of the United States Patent and Trademark Office (USPTO), checked in November 2026.
Deadlines that set the search timetable
An IPR petition is barred if it is filed more than 1 year after the petitioner, its real party in interest or a privy is served with an infringement complaint. A joinder request is the exception under 35 U.S.C. 315. A PGR petition must be filed within 9 months of grant.
The search sits inside that year. Declarations and the petition follow it, so the search usually starts soon after service.
How an IPR prior art search is carried out
An IPR prior art search usually follows these steps:
- The critical date: the searcher checks the priority chain, since a claim without support in an earlier application takes a later date.
- The prosecution history: it shows the examiner’s art and the reasons for allowance.
- Art beyond the examiner’s: the Director may reject a petition that relies on substantially the same art or arguments the Office has already considered.
- All document types: standards, theses, manuals, foreign patents and other non-patent literature often hold the closest art.
- Proof of public accessibility: library records and archive captures date each document.
- Claim mapping: a ranked list of references, with charts that cite exact passages.
The charts follow the structure of an invalidity claim chart. Step 4 is covered in the guide to finding prior art for invalidity, and the method matches a full invalidity search.
Why estoppel changes the scope of the search
Estoppel is a main reason why an IPR prior art search is broad. After a final written decision, the petitioner cannot raise in court or at the Office any ground that it raised or reasonably could have raised in the IPR.
Art that a skilled searcher could have found before filing may therefore be lost for later litigation. That risk is permanent. For this reason, a search for a petition is usually as thorough as a search for trial.
Discretionary denial and the search
Since 2025 the USPTO Director has decided whether to deny IPR and PGR petitions on discretionary grounds. In January 2026 several of these decisions were designated precedential or informative. From 16 November 2026 the PTAB again decides the merits at institution, and the Director keeps the discretionary questions. Strong art does not remove that risk. An early search lets the attorney judge the merits before the fees are paid.
Commission an IPR prior art search
To plan an IPR prior art search or a PGR search, send us the patent number with its key dates through our patent invalidity search service. Invalidity searches at Synoptic IP cost USD 1,200–10,000 and take 1–3 weeks (November 2026).
This guide is general information and is not legal advice.
Frequently Asked Questions
Can product prior art be used in an IPR?
Not as the product itself, because an IPR ground can rest only on patents and printed publications. A dated manual, brochure or datasheet that describes the product can be used, provided the petitioner shows that it was publicly accessible in time.
How long does a prior art search for an IPR take?
At Synoptic IP, invalidity searches take 1–3 weeks once the scope is agreed, as of November 2026. The time depends mainly on the number of claims, the length of the priority chain and the languages to be searched. The search should finish well before the 1-year bar, because the declarations and the petition still have to follow it.
Can art cited by the examiner be used in an IPR petition?
Yes, although the Director may deny a petition that relies on the same or substantially the same art or arguments that the Office already considered. A petition based on examiner art usually has to show that the Office erred in a way material to patentability. New references found by the search are often the stronger basis.
Who can file an IPR petition?
Any person who is not the owner of the patent can file an IPR petition. The petitioner must certify that it is not barred or estopped, and it must name every real party in interest. A party that has already filed a civil action challenging the validity of a claim cannot then petition for IPR.
Is post-grant review available for every patent?
No, post-grant review applies only to patents under the first-inventor-to-file rules, broadly those with a claim whose effective filing date is on or after 16 March 2013. The petition must also be filed within 9 months of grant or reissue. Older patents and later challenges go to inter partes review instead.