Over five years have passed since the patent opposition system was introduced in Japan on April 1, 2015. Now, as a way of invalidating a granted patent right, the patent invalidation trial system, which traditionally exists, and the patent opposition system coexist.

(Comparison of the two systems is as described in our Newsletter dated on June 5, 2015 (http://www.rc-iplaw.com/newsletter/patent2/). Note that, if an opposition to a patent and an invalidation trial against the patent are pending at the same time, in principle, the invalidation trial is examined with higher priority.

  In the period before and after the introduction of the patent opposition system (from 2010 to 2019), the number of cases of utilizing the patent invalidation trial system and the patent opposition system (from 2015 to 2019) etc. is as follows.
(https://www.jpo.go.jp/resources/report/nenji/2020/document/index/0107.pdf#page=6)

  As illustrated below, the number of requests for invalidation trial is over 200 from 2010 to 2015, but it is less than 200 after 2016.

  On the other hand, the number of filed patent oppositions is 364 in 2015, the first year of the introduction of the system, but it is greater than 1,000 after 2016.

  In view of the increased number of filed patent oppositions, it can be considered that there was a strong need for the introduction of the patent opposition system.

  By the way, since the number of filing the oppositions is larger than that of the invalidation, the number of patent revocation decisions is greater than the number of invalidation decisions to the requests for invalidation trials (in other words, a greater number of patent rights are revoked through the patent opposition system, than invalidated through the invalidation trials); however, the rate of patent revocation decisions is definitely not high.

  Results of examination of 4,977 oppositions filed from April 2015 to the end of December 2019, as of the end of December 2019 (including 532 cases which were pending at that time), are as illustrated below.

(Statistical information on the Patent Opposition, cited from the website of JPO, Ministry of Economy, Trade and Industry (jpo.go.jp))
  As seen, all or a part of claims subject to the opposition were revoked ("Patent Revoked") only in 509 cases (10.2%).

  Reasons of these results can be considered as: the patent opposition is required to be filed within 6 months from the date of issue of the patent publication, and thus, some oppositions may be filed with insufficient evidences, while the patent invalidation trial is filed after collecting reasons for the invalidation; and, the quality of examination of patent applications is improved, which reduces such cases that a patent is granted for an application which may be easily revoked.

  Another reason may be that patentees (of a patent to which an opposition is filed) file a request for correction to avoid revocation of the patent.

  However, such a request for correction can be considered as not a little favorable to a party who filed the patent opposition since the claims subject to the opposition are deleted or restricted by the correction.  Thus, in addition to 509 oppositions (corresponding to 10.2%) in which all or a part of claims subject to the opposition were revoked ("Patent Revoked"), 2,255 oppositions (corresponding to 45.3%) in which a granted patent was decided to be maintained through the correction of the claims etc. ("Patent Maintained (w/ Correction)"), and 52 oppositions (corresponding to 1.0%) which were dismissed as a result of deletion of all the claims subject to the opposition ("Opposition Dismissed (w/ Correction)") can be taken into consideration, and thus, the substantial success rate of the oppositions can be 56.6% at maximum.

  Therefore, in view of costs and efforts for the opposition and the invalidation trial, it is preferred to positively file an opposition, if it is within the allowed period for filing an opposition to the patent.