Comparing Post-Grant Procedures at the USPTO, EPO and JPO

Companies with global portfolios often face the same invention in patents granted by several offices. Each major office provides a way to challenge a granted patent administratively, without going to court. The U.S. Patent and Trademark Office, the European Patent Office (EPO) and the Japan Patent Office (JPO) take different approaches, and the differences in timing, available grounds and legal effect affect how parties coordinate their challenges.

This page gives a high-level comparison. Details of foreign procedure, fees and deadlines should be confirmed with the relevant office.

United States: PGR, IPR and ex parte reexamination

The USPTO has three main post-grant tools for third parties.

• Post-grant review (PGR) must be filed within nine months of grant and is available only for patents with an effective filing date on or after March 16, 2013. It allows most invalidity grounds, including §§ 101, 102, 103 and 112. See the post-grant review guide.
• Inter partes review (IPR) may be filed after the nine-month PGR window, or after any PGR ends. It is limited to §§ 102 and 103 based on patents and printed publications, and it is subject to a one-year bar if the petitioner was served with an infringement complaint. See the inter partes review guide.
• Ex parte reexamination may be requested by anyone, including the patent owner, at any time during the period of enforceability, based on a substantial new question of patentability raised by patents or printed publications. After the order, the proceeding is conducted between the Office and the patent owner. See the ex parte reexamination guide.

PGR and IPR are trials before the Patent Trial and Appeal Board, with limited discovery and a final written decision, and both carry estoppel. Reexamination is handled by examiners in the Central Reexamination Unit.

European Patent Office: opposition

A European patent may be opposed at the EPO within nine months of publication of the mention of grant in the European Patent Bulletin (Art. 99 EPC). Any person other than the proprietor may file, and the opposition fee must be paid within the same period.

The grounds are set out in Art. 100 EPC:

• The subject matter is not patentable under Arts. 52 to 57 EPC, which covers novelty, inventive step, industrial application and excluded subject matter
• The patent does not disclose the invention clearly and completely enough for a skilled person to carry it out
• The subject matter extends beyond the content of the application as filed

The opposition is decided by an opposition division. Its decision may be appealed to the Boards of Appeal. The outcome is that the patent is revoked, the opposition is rejected, or the patent is maintained in amended form, and that result applies centrally for all states in which the patent has effect (Art. 101 EPC). After the opposition period, challenges generally move to national courts or, for participating states, the Unified Patent Court.

Japan Patent Office: opposition and invalidation trials

Japan reintroduced a post-grant opposition system in 2015. An opposition may be filed within six months of publication of the patent gazette. It is decided by a panel at the JPO and is designed as a comparatively streamlined route for third parties to ask the Office to reconsider a recent grant.

Separately, Japan provides invalidation trials, which may be requested by an interested party at any time. Invalidation trials are adversarial and are commonly used alongside infringement disputes. Both procedures are handled within the JPO’s trial and appeal system, and decisions can be challenged in the courts.

Side-by-side comparison

	USPTO PGR	USPTO IPR	USPTO ex parte reexam	EPO opposition	JPO opposition	JPO invalidation trial
Timing	Within 9 months of grant	After the 9-month window; one-year bar if sued	Any time during enforceability	Within 9 months of mention of grant	Within 6 months of gazette publication	Any time
Who can file	Anyone but the patent owner	Anyone but the patent owner	Anyone, including the owner	Anyone but the proprietor	Third parties	Interested parties
Grounds	Most invalidity grounds, incl. §§ 101, 112	§§ 102, 103 on patents and printed publications	Patents and printed publications	Art. 100 EPC	Statutory grounds, broadly patentability-based	Statutory grounds
Decision-maker	PTAB panel	PTAB panel	Examiner (CRU)	Opposition division	JPO panel	JPO panel
Effect	Claims canceled or confirmed; estoppel	Claims canceled or confirmed; estoppel	Claims canceled, confirmed or amended	Revoked, maintained or amended for all designated states	Revoked or maintained	Invalidated or upheld

For a broader chart of U.S. options, see the PGR comparison chart.

Coordinating challenges across offices

A few practical points follow from the comparison:

• Early windows overlap. The EPO and U.S. PGR windows are both nine months, and the JPO window is six, so a party monitoring competitors’ patents may need to decide early about parallel challenges.
• Grounds differ. Arguments based on added matter or sufficiency at the EPO have counterparts in U.S. written description and enablement, which are available in PGR but not IPR.
• Effects differ. An EPO decision acts centrally across designated states, while U.S. and Japanese decisions affect only the national patent.
• Positions travel. Arguments and amendments made in one office may be cited in another. Consistency across proceedings matters.

For the U.S. comparison in more detail, see PGR vs. IPR.

Key takeaways

• The USPTO offers PGR (nine months), IPR (after nine months) and ex parte reexamination (any time).
• EPO opposition must be filed within nine months of the mention of grant, by anyone but the proprietor, on Art. 100 EPC grounds, and acts centrally.
• The JPO offers an opposition within six months of gazette publication, reintroduced in 2015, and invalidation trials available at any time to interested parties.
• Timing, grounds and effect differ enough that global challenges need coordination.