PatentBrief

Post-grant · Challenges

How a granted patent gets killed.

Since the America Invents Act, the most common way to invalidate a patent isn't a jury — it's a panel of administrative judges at the Patent Trial and Appeal Board. Inter partes review is faster, cheaper, and easier to win than a courtroom fight. Here's how it works.

The essentials

IPR at a glance

Who can file
Anyone who is not the patent owner — typically a company the owner has sued or threatened for infringement.
When
More than nine months after grant (and after any post-grant review ends). An accused infringer generally must petition within one year of being sued.
Grounds
Only novelty (§102) and obviousness (§103), and only based on patents and printed publications — not on §101 or §112.
Standard of proof
Preponderance of the evidence — a lower bar than the 'clear and convincing evidence' required to invalidate a patent in court, which is why challengers prefer it.
Who decides
A panel of three Administrative Patent Judges at the Patent Trial and Appeal Board (PTAB) — not a jury.
Estoppel
A petitioner who gets a final decision cannot later raise, in court, any ground it raised or reasonably could have raised in the IPR.

Don't confuse them

IPR vs PGR vs reexamination

Inter Partes Review (IPR)

When · 9+ months after grant

Grounds · §102 / §103, on patents & printed publications only

The workhorse. Fast, evidence-heavy, and very common as a parallel track to infringement litigation.

Post-Grant Review (PGR)

When · Within 9 months of grant

Grounds · Any ground — §101, §102, §103, §112

Broader than IPR but only available in a short window right after the patent issues, so it's used less often.

Ex Parte Reexamination

When · Any time during the patent's life

Grounds · §102 / §103, on patents & printed publications

Anyone (including the owner) can request it; an examiner — not a judge panel — re-examines the claims. No trial, and the requester doesn't participate.

The path of a review

Six stages of an IPR

  1. 01

    Petition

    The challenger files a petition identifying the claims and the prior-art grounds, with expert declarations.

  2. 02

    Patent owner's preliminary response

    The owner may respond, arguing the petition fails to show a reasonable likelihood of success.

  3. 03

    Institution decision

    Within about six months of the petition, the Board decides whether to institute the review. It's discretionary — many petitions are denied.

  4. 04

    Trial

    If instituted, the parties take limited discovery, depose experts, and brief the merits before the three-judge panel.

  5. 05

    Final written decision

    The Board issues a final decision within twelve months of institution (extendable by six), ruling each challenged claim patentable or unpatentable.

  6. 06

    Appeal

    Either side can appeal the decision to the Court of Appeals for the Federal Circuit.

The bigger picture

IPR is usually a parallel track.

Most IPRs are filed by a company being sued, to invalidate the patent while the lawsuit runs. Because the grounds are §102 and §103, the same prior-art questions drive both.

Patent litigation →Non-obviousness (§103) →Prior art & novelty →

FAQ

IPR & the PTAB — common questions

What is an inter partes review (IPR)?

An IPR is a trial-like proceeding at the USPTO's Patent Trial and AppealappealAfter repeated rejections, an applicant can appeal to the PTAB — and from there to federal court. Slow and expensive.Read more → Board where someone other than the patent owner asks a panel of three administrative judges to cancel a granted patent's claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more → as not novel (§102) or obvious (§103), based on prior-art patents and publications.

How is IPR different from a patent lawsuit?

It's at the Patent Office, not a court; decided by patent judges, not a jury; limited to §102/§103 prior-art grounds; and uses a lower burden of proof (preponderance of the evidence vs. clear and convincing in court). It's usually faster and cheaper, which is why accused infringers file IPRs alongside their court cases.

Who can file an IPR?

Anyone who is not the patent owner, more than nine months after the patent granted. A company sued for infringementinfringementMaking, using, selling, or importing a patented invention without permission from the patent holder.Read more → generally must file within one year of being served with the complaint.

What is the PTAB?

The Patent Trial and AppealappealAfter repeated rejections, an applicant can appeal to the PTAB — and from there to federal court. Slow and expensive.Read more → Board is the USPTO tribunal of administrative patent judges that hears IPRs, post-grant reviews, and appeals from examinerexaminerThe USPTO official who reviews a patent application and decides whether to grant it.Read more → rejections. Its final decisions can be appealed to the Federal Circuit.

Plain-English education, not legal advice. PTAB proceedings have strict deadlines (an accused infringer generally has one year from being sued to file) and complex estoppel consequences — consult experienced patent counsel before filing or responding. PatentBrief is not a law firm.

Keep going · Enforcement

InfringementWhat counts as infringing — and what to do about it.LitigationThe stages of a suit, the remedies, and the defenses.LicensingTurning the right into revenue instead of a lawsuit.