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2 Ways to oppose a granted Patent in Japan: Invalidation Trial & Opposition

After the grant of a patent third parties have mainly two options to oppose a patent. These are filing an invalidation trial and filing an opposition. In this article, we want to explain these two options and briefly talk about an additional option.

Filing an Opposition in Japan

The opposition system for patents has existed in Japan for a long time. It was introduced in 1921 as a system that can be used before a patent is granted. In 1994, it was changed to a system that can be used after a patent is granted. After a temporary pause of the system since 2003, a new opposition system came into effect in April 2015. The new system was introduced to ensure stronger patent rights.

The deadline for filing an opposition is within 6 months after the granted patent was published in the patent gazette. Anyone can file an opposition. The process is quick, and no oral hearings are involved. On average it took 5.8 months in 2016 to achieve a decision

After an opposition was filed, the JPO will examine and consider whether there are any reasons for revocation. If yes, they are notified to the patentee and they can file a reply and/or amendments. The opponent can file remarks in cases of amendments and again the JPO will check for reasons for revocation. If they find one again both parties have the chance to file remarks and amendments and a final decision by the board to maintain or revoke the patent will be issued. The patentee can appeal the decision, but the opponent cannot.

According to the JPO status report for 2020 that we also discussed in this blog post, in 2019, 1073 oppositions were filed which is a similar number to the previous year.

Filing an Invalidation Trial in Japan

Unlike an opposition, an invalidation trial can be filed any time after the issuance of a patent, in some cases even after the patent already has expired. However, only interested parties can file an invalidation trial. The procedure is slightly more time consuming than the opposition. In 2016 the average until a decision was 10.5 months.

After a request for invalidation was filed with the JPO by the opponent, the patentee can file a written answer and amendments to the patent claims. In response, the opponent can provide more evidence. The next step in an invalidation trial is oral hearings. Then the JPO will issue an advance notice of trial and the patentee again has the chance for amending the patent. Finally, the JPO will issue a decision to either grant all the claims of the opponent, a part of the claims of the opponent, none of the claims or to reject the invalidation trial. Both parties can appeal the decision at the Intellectual Property High Court.

According to the JPO status report 2020, in 2019, 112 invalidation trials were filed which is a fairly low number.

Comparison of Opposition and Invalidation Trial in Japan


  Opposition Invalidation Trial
Deadline 6 months after publication No deadline
Demandee Anyone Interested party
Oral Proceedings No Yes
Timeframe until decisions About 6 months About 10 months
Appeal Patentee can appeal Both parties can appeal

 Other options for opposing granted Patents

Besides the two options, third parties can also file observations. These can be filed after the patent is granted but also before the grant. Anyone can file observations and anonymous filing is possible. When filing a third-party observation, you cannot contact examiners directly however you can receive feedback as to whether the documents you filed were used. To prevent a patent from being granted you must file the observations before a notice of grant is issued.

We hope you found our short overview helpful. If you are currently considering opposing a Japanese patent or are in the position of being opposed, we can help you with the necessary translations and also provide a translator’s affidavit in case it is required by the court. Just contact us through our contact form.

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