Introduction
In the complex world of intellectual property law, patents play a crucial role in fostering innovation by granting inventors exclusive rights to their inventions. However, not all granted patents are legally robust. Sometimes, patents are issued despite lacking novelty, non-obviousness, or adequate disclosure. Challenging such patents has become a central strategy in competitive markets. Two essential tools for patent invalidation are Post-Grant Review (PGR) and Inter Partes Review (IPR) — proceedings instituted under the America Invents Act (AIA) of 2011.
Understanding PGR and IPR mechanisms is crucial for businesses, inventors, and legal professionals seeking to navigate the competitive IP landscape. This article explores these two proceedings, compares their strengths and limitations, and lays out strategic considerations for effectively invalidating patents.
Understanding Post-Grant Review (PGR)
Definition and Purpose
Post-Grant Review is a trial proceeding conducted at the Patent Trial and Appeal Board (PTAB) to review the patentability of one or more claims in a patent. PGR allows third parties to challenge a patent immediately after it is granted.
Timeline of PGR process — USPTO (public domain)
Eligibility and Timeframe
Only available for patents filed under the AIA (on or after March 16, 2013).
Must be filed within nine months after a patent is granted or reissued.
Grounds for Filing
Broad grounds: Almost any invalidity argument can be raised — including:
Lack of novelty (35 U.S.C. § 102)
Obviousness (35 U.S.C. § 103)
Lack of patentable subject matter (35 U.S.C. § 101)
Lack of written description or enablement (35 U.S.C. § 112)
Procedural Overview
Filing of a Petition
Preliminary Response by Patent Owner
Institution Decision by PTAB
Trial Phase
Final Written Decision (within 12 months of institution)
Understanding Inter Partes Review (IPR)
Definition and Purpose
Inter Partes Review is another PTAB proceeding that allows third parties to challenge the validity of patent claims based only on prior art consisting of patents or printed publications.
Typical IPR process flow — USPTO (public domain)
Eligibility and Timeframe
Available for any patent, regardless of the filing date.
Must be filed after the later of:
Nine months after the grant of a patent, OR
Termination of any PGR proceeding.
Grounds for Filing
Limited to novelty and obviousness based on:
Prior patents
Prior printed publications
Procedural Overview
Filing of a Petition
Preliminary Response
Institution Decision
Discovery and Trial
Final Written Decision
Comparison Between PGR and IPR
| Feature | PGR | IPR |
|---|---|---|
| Filing Deadline | Within 9 months after grant | After 9 months or after PGR concludes |
| Grounds for Challenge | Broad (Sections 101, 102, 103, 112) | Limited (Sections 102 and 103 only) |
| Prior Art | Any (public use, sale, publications, patents) | Patents and printed publications only |
| Estoppel Scope | Broad (any issue that was or could have been raised) | Narrower (only issues actually raised or reasonably could have been raised) |
| Cost | Higher due to broader issues | Lower comparatively |
| Popularity | Less frequently used | More commonly used |
Strategies for Patent Invalidation
Successfully invalidating a patent via PGR or IPR requires more than merely identifying weak points in a patent — it demands tactical planning, compelling evidence, and strategic litigation management.
1. Timing and Forum Selection
Choosing between PGR and IPR often comes down to timing:
PGR: If possible, filing early allows for broader challenges.
IPR: If outside the 9-month window, IPR is the best option.
Tip: Monitor newly issued patents carefully to exploit PGR opportunities.
2. Comprehensive Prior Art Search
A thorough prior art search is the cornerstone of an effective petition. Strategies include:
Searching non-patent literature (NPL), especially for PGR.
Using foreign patents and technical journals.
Engaging professional prior art search firms or experts.
Tip: The best prior art is not always the oldest — it is the most relevant and enabling.
3. Drafting a Strong Petition
Key elements of a persuasive petition:
Clearly map the claims to prior art references.
Use expert declarations to support arguments.
Construct logical, methodical, and easy-to-follow invalidity grounds.
Tip: Anticipate counterarguments and preemptively address them in the petition.
4. Managing Discovery
Discovery in PGR and IPR is limited compared to federal court litigation but can be pivotal:
Use depositions of experts effectively.
Request necessary documents through targeted discovery requests.
Tip: Avoid fishing expeditions; narrowly tailored discovery requests are more likely to be granted.
5. Settlement Considerations
Settlement is possible before the final written decision:
Advantages: Save costs and uncertainty.
Risks: Public perception of weakness.
Tip: Always negotiate from a position of strength, showing you are prepared to go the distance.
6. Preparing for Appeals
If the PTAB’s decision is adverse, appealing to the Federal Circuit is the next step:
Appeals must be based on the record developed during PGR or IPR.
Success rates on appeal vary but are not negligible.
Tip: Ensure that important issues are properly preserved during the PTAB proceedings.
Recent Trends and Case Studies
Trend: Increasing use of IPRs by technology and pharmaceutical companies as part of broader IP litigation strategies.
Example 1: Apple Inc. v. VirnetX Holding Corp.
Apple filed multiple IPRs challenging VirnetX patents critical to ongoing litigation.
Some claims were invalidated, significantly weakening VirnetX’s leverage.
Example 2: Oil States Energy Services v. Greene’s Energy Group
Landmark Supreme Court decision affirming the constitutionality of IPR proceedings.
Challenges and Criticisms of PGR and IPR
Criticisms
Patent Owners’ Concerns: Allegations of “death squads” for patents.
Procedural Issues: Some argue PTAB proceedings favor petitioners unfairly.
Constitutional Challenges: Questioning administrative invalidation of property rights.
Challenges for Petitioners
Narrow grounds of appeal.
High estoppel risks after a final written decision.
Conclusion
Post-Grant Review and Inter Partes Review have transformed the landscape of patent litigation by offering relatively faster, less expensive alternatives to traditional district court challenges. Mastering the art of patent invalidation through these mechanisms requires:
Strategic selection between PGR and IPR,
A deep dive into prior art,
Meticulous petition drafting,
Tactical discovery management,
Agile settlement and appeal strategies.
Both PGR and IPR are powerful weapons in the hands of skilled practitioners. However, they demand a proactive, evidence-driven approach and careful navigation of procedural nuances to achieve success. As the PTAB evolves and new precedents are set, staying ahead of trends will remain vital for any party engaged in patent disputes.
