Inter partes review is one of the most powerful mechanisms in modern U.S. patent law for challenging the validity of an issued patent. Introduced by the America Invents Act in 2012, inter partes review allows any person who is not the patent owner to petition the Patent Trial and Appeal Board to cancel one or more claims of an issued patent. Since the PTAB began accepting IPR petitions, thousands of patents have been challenged — and many have had their claims cancelled or significantly narrowed. At PerspireIP, we represent both petitioners and patent owners in IPR proceedings. This guide explains how inter partes review works and how to use it strategically.
What Is Inter Partes Review?
Inter partes review is a trial proceeding conducted before the Patent Trial and Appeal Board to challenge the patentability of one or more claims of an issued patent. IPR petitions may only raise challenges based on prior art patents or printed publications under 35 U.S.C. 102 (anticipation) or 103 (obviousness). Other invalidity challenges — such as Section 101 patent eligibility or Section 112 written description — cannot be raised in an IPR and must be pursued in district court litigation instead.
An IPR petition must be filed within one year of the petitioner (or a real party in interest or privy of the petitioner) being served with a complaint alleging infringement of the challenged patent. This one-year bar is strictly enforced — failing to file before it expires results in the petitioner losing their right to pursue inter partes review on the challenged patent.
The IPR Process: Step by Step
The inter partes review process has several distinct phases, each with important deadlines and procedural requirements.
Filing the IPR Petition
The process begins with the petitioner filing an IPR petition with the PTAB, accompanied by a filing fee (currently $19,500 for up to 20 claims), a supporting brief identifying the challenged claims and the grounds for challenge, and any supporting declarations from technical experts. The petition must demonstrate that there is a reasonable likelihood that the petitioner would prevail on at least one challenged claim — the standard for institution of an IPR trial.
Patent Owner Preliminary Response
The patent owner has 3 months to file a preliminary response to the IPR petition. This response argues that the petition should not be instituted — that the petitioner has not met the reasonable likelihood standard, that the challenged art does not actually teach the claimed elements, or that there are procedural defects in the petition. The preliminary response is often the patent owner’s best opportunity to prevent institution of an IPR trial, which is a critical threshold because IPR petitions that are instituted result in claim cancellation at a high rate.
Institution Decision
Within 3 months of the patent owner’s preliminary response (or 6 months after the petition if no preliminary response is filed), the PTAB issues an institution decision. The PTAB institutes the IPR if it determines there is a reasonable likelihood that the petitioner would prevail on at least one challenged claim. If the PTAB institutes, the full trial proceeds. If the PTAB denies institution, the proceeding ends and the petitioner cannot file another IPR petition on the same patent raising the same or reasonably could have raised grounds.
IPR Trial
After institution, the parties engage in discovery, file additional briefs, and may submit supplemental expert declarations. The trial phase culminates in oral argument before a three-judge PTAB panel, after which the PTAB issues a final written decision within one year of institution (extendable to 18 months for good cause). The PTAB applies a preponderance of the evidence standard — claims are cancelled if the challenger demonstrates invalidity by a preponderance of evidence, a lower standard than the clear and convincing evidence required in district court litigation.
Strategic Uses of Inter Partes Review
Inter partes review can be a powerful strategic tool for both challengers and patent owners.
- Defensive IPR: companies facing patent infringement lawsuits routinely file IPR petitions as a defensive strategy, seeking to invalidate the asserted patent at the PTAB while district court litigation is stayed.
- Offensive IPR: companies can use IPR to clear competitor patents that are blocking market entry or creating licensing demands.
- Patent quality improvement: IPR petitions can be used to challenge patents that should not have been granted due to prior art the examiner missed.
- Licensing leverage: the threat of an IPR petition can be used as negotiating leverage to reach favorable patent licensing terms.
Defending Your Patent in an IPR
Patent owners facing an inter partes review petition must mount a vigorous defense at the institution stage and, if the IPR is instituted, throughout the trial. Key defense strategies include filing a detailed and persuasive patent owner preliminary response, seeking to amend claims if the original claims are vulnerable, presenting compelling expert testimony on the differences between the invention and the prior art, and arguing secondary considerations of non-obviousness such as commercial success, long-felt need, and industry praise. Patent owners may also consider settling with the petitioner in exchange for a licensing arrangement.
IPR Estoppel Considerations
An important strategic consideration in inter partes review is the estoppel that applies after the PTAB issues a final written decision. After a final decision, the petitioner (and real parties in interest) may not assert in any proceeding before the USPTO, district court, or ITC that a challenged claim is invalid on any ground that was raised or could have been raised during the IPR. This estoppel is significant — it means that a petitioner who unsuccessfully challenges a claim in an IPR may be barred from raising the same or related invalidity arguments in litigation.
How PerspireIP Handles IPR Proceedings
PerspireIP represents clients on both sides of inter partes review proceedings. For petitioners, we analyze patent vulnerability, identify the strongest prior art grounds, draft persuasive petitions and supporting expert declarations, and manage the full IPR trial process. For patent owners, we evaluate incoming IPR petitions, develop comprehensive preliminary response strategies, coordinate expert witnesses, and defend patents through trial and any subsequent appeal to the Federal Circuit.
Conclusion
Inter partes review has fundamentally changed the patent litigation landscape, providing a faster, cheaper alternative to district court invalidity challenges. Whether you are considering filing an IPR petition to challenge a competitor’s patent or you are a patent owner who has received an IPR petition, strategic and experienced legal counsel is essential. PerspireIP has the expertise to guide you through every phase of the inter partes review process. Contact us today to discuss your IPR strategy.