The Japan Patent Office (JPO) has published statistics related to the use of the patent opposition system that has been in operation in Japan since April 2015. These are summarized below.
 
Please refer to the following URL:
http://www.jpo.go.jp/torikumi_e/t_torikumi_e/status_oppositions_note_procedures.htm
 
According to the JPO report, active use of the opposition system began in about October 2015, and, as of June 2017, approximately 110 oppositions were being filed each month. As shown in the statistics, among cases filed in 2015 and 2016 in which a final decision has been delivered, between 40 and 50% of the opposed patents were maintained without correction. Further, approximately 10% of opposed patents have been revoked.

Outline of the Japanese Opposition System
While an opposition system also existed in Japan previously, the system was such that the party filing the opposition was unable to participate in deliberations, and since there were many cases in which proceedings between the same parties in opposition trials and invalidation trials would overlap, the system was abolished under the patent law revisions of 2003 and integrated with the invalidation trial system. However, since, for example, subsequent concerns were expressed that the burden on the parties concerned is comparatively heavy in invalidation trials and that the system was difficult to use for universities and the like and, further, the need to expedite the acquisition of strong and stable rights had increased as a result of corporate globalization, the opposition system was re-introduced under a 2014 revision to the Patent Law. The main features of the current opposition system are outlined below.
 

Opposition Period	Within 6 months of the date of publication in the Patent Gazette
Eligible to Oppose	Any party
Reasons for Opposition	Reasons of public interest (such as novelty, inventive step, and deficiencies in the description of the specification)
Format of Deliberations	Documentary deliberations by a trial board (no oral proceedings)
Scope of Opposition	Per claim
Sua Sponte Proceedings	Sua sponte reasons for revocation may be included in the trial deliberations by the Opposition Board.
Involvement of Patent Right Holder in Proceedings	When notified of reasons for revocation, the patent right holder may submit written arguments and/or correct claims.
Involvement of Opposing Party in Proceedings	When claims are corrected by the patent right holder, the opposing party may subsequently submit written arguments.
Fees	Lower than for an invalidation trial
Appeal	Only possible with respect to a Decision of Revocation

Comparing the current opposition system to the previous system, while the systems are largely the same in terms of period, eligibility and permissible reasons for opposition, certain aspects have changed, such as the opposing party being able to submit written arguments after claim corrections by the patent right holder. In particular, since the format of trial proceedings is now entirely document-based, the system has become easier for opposing parties to use as there is no longer any possibility of the parties concerned being summoned to oral proceedings.
 
Further, under the current opposition system, it is possible for either the Opposition Board or the patent right holder to request an interview between the Opposition Board and the patent right holder. Since the opposition system is not an adversarial system, interviews with the opposing party are, in principal, not permitted unless the Opposition Board determines that there is a need to solicit technical explanation.

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Summary prepared by International Information Group
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