1. 1. Introduction

 In Japan, for any defendant in infringement proceedings of patent or the like, a protection by an invalidity defense (Patent Act Article 104-3) in the proceedings is available. In addition to an invalidity defense mentioned above, a defendant can make an attack for a retroactive effect of lapse of a patent right by separately requesting a trial for patent invalidation (hereinafter abbreviated as a trial for invalidation) (Patent Act Article 123(1)) (so called a strategy of double track). Under the Code of Civil Procedure and Patent Act, infringement proceedings and a trial for invalidation are respectively independent. Accordingly, when infringement proceedings are instituted, it is not always necessary to request a trial for invalidation so that whether to request a trial for invalidation depends on defendant's discretion.

 In Japan, since many defendants of infringement proceedings of patent or the like comparatively choose the strategy of double track, a trial for invalidation is requested in parallel in approximately 50 to 67 % of infringement proceedings (district court level) claiming an invalidity defense (according to the data in the years 2011 to 2015 published from Japan Patent Office (JPO)). As an example of background in which the strategy of double track is easily adopted, it can be pointed out that a certain mentality of a defendant is in effect, which assumed that a second instance can be maintained to find the way of avoiding infringement eventually (victory in a second instance) or seeking an amicable settlement, if a defendant can win a victory in either a decision of a district court or a trial decision of a trail for invalidation (unless a defendant loses both).

 Thus, it appears to be safer to choose the strategy of double track under the Japanese judicial system in which a patent right cannot be executed unless a patent owner wins a victory in both a district court and a trail for invalidation. However, even this strategy of double track may lead to unexpected failure if wrongly handled.

2. 2. Recent judicial precedents

2-1. Failed example for a strategy of double track

 'Decision of Intellectual Property High Court on December 18, 2018 (2017 Appeal Case No. 10086, Skin Beautifying Roller Case)' (hereinafter referred to as "the subject Judicial Precedent") is a judicial precedent of a typical failure case of the strategy of double track.

2-2. An invalidity defense in the initial instance, and a trial for invalidation proceeded in parallel therewith

 In the subject initial instance, the defendant claimed an invalidity defense for lack of an inventive step as a ground for invalidation (Patent Act Articles 123(1)(ii) and 29(2)). Also, the defendant initiated a trial for invalidation for the same reason for invalidation as double track with the proceedings.

 The court recognized the defendant's defense and rejected plaintiff's claim in the initial decision (in favor of defendant). On the other hand, JPO rendered the trial decision that the defendant's claim is not admissible in the trial for invalidation (against the defendant who is a demandant for the trial). At this point, decisions in the same ground for invalidation were divided between JPO and the court.

 After that, the plaintiff (the patent owner) was dissatisfied with this decision and appealed to a higher court. On the other hand, the trial decision became final and binding since the defendant did not file a litigation for rescinding the trial decision.

2-3. Decision made by the court of second instance

 In the second instance, the defendant (appellee) claimed an invalidity defense for lack of an inventive step as the ground 1 for invalidation same as claimed in the initial decision. Additionally, the defendant claimed an invalidity defense for lack of an inventive step as the ground 2 for invalidation by submitting a new document. However, the court rejected defendant's contention as a ground that claiming the same ground 1 for invalidation as claimed in the trial for invalidation, in which the decision was made as being inadmissible is against the principle of faith and trust (the Code of Civil Procedure, Article 2) from the purport of Patent Act, Article 167 (Prohibition of double jeopardy).

 Furthermore, the court rejected defendant's contention by a ground that "the ground 2 for invalidation shows an intention to rehash the subject trial decision in which appellee's contention was rejected so that this is the contention for invalidation based on substantially 'the same fact and the same evidence'".

2-4. Decision

 The main abstract of the subject Judicial Precedent is cited as follows:

 'It is construed that the purport of Patent Act, Article 167, in which any repeated request of a trial for invalidation based on the same fact and the same evidence between the same parties is not permitted, is to realize one-time settlement of dispute between the same parties. However, such purport shall not be applied only to the procedure of a trial for invalidation.

 Then, if a defendant of infringement proceedings files a request of a trial for invalidation and the decision that the request for the invalidation trial is inadmissible becomes final and binding without filing a litigation for rescinding the trial decision, it should be construed in light of the purport of the Code of Civil Procedure, Article 2 that claiming a ground for invalidation based on the same fact and the same evidence in the infringement proceedings instituted between the same parties as a patent invalidity defense in accordance with Patent Act Article 104-3(1) is not permitted due to the violation of the principle of faith and trust under the proceedings unless there are exceptional circumstances. Since it appears that there are no such exceptional circumstances, it is not permissible for the appellee to claim ground 1 for invalidation as a patent invalidity defense in the subject proceedings.'

 Moreover, there has been a judicial precedent to reject a contention of a ground for invalidation violating the effect of prohibition of double jeopardy since the contention does not satisfy the requirement that "it is recognized to be invalidated ... by a trial for patent invalidation". Therefore, this 'conclusion' in which 'the contention of a ground for invalidation violating the effect of prohibition of double jeopardy should be rejected' is not particularly new even if the interpretation of application of the law in middle stage is different in accordance with the difference of background of proceedings.

<*The past judicial precedent shows the case that a trial decision of invalidation became final and binding through a litigation rescinding the trial decision.>

2-5. Discussion of the subject Judicial Precedent

 The point of the subject Judicial Precedent is that the defendant had a trial for invalidation, which was initiated under the same ground for invalidation as the one to be claimed in the second instance, and the trial decision became final and binding with a trial for invalidation inadmissible despite that the defendant did not run out of measures to appeal, and therefore, the defendant became unable to claim the ground for invalidation in the infringement proceedings.

 In the reasons for the court decision, the court did not show any particular reason of adopting violation of the principle of faith and trust (the Code of Civil Procedure, Article 2) under judicial proceedings. However, for example, it is possible to presume the reason as stated below. That is, although the defendant accepted the final and binding decision of being inadmissible to invalidate a patent under the circumstances where a defendant does not run out of measures to appeal, which is equal to giving up its own contention of invalidation of the patentsp right, the defendant still claimed invalidation of the patent right in infringement proceedings. This defendant's action leads to betray plaintiff's expectation that "a defendant already gave up the contention of invalidation of the patent right" and, thus, it is not permissible under the principle of faith and trust.

 Additionally, although the reason why the defendant had the decision of rejection in the trial for invalidation become final and binding by itself is unknown in the documents of the proceedings, it is clear to have an intention at least to avoid infringement in light of the contention that the defendant kept claiming invalidation of the patent right even in the second instance. Therefore, we have no choice but to determine that it was an obvious error in the proceeding strategy to have the decision of rejection in the trial for invalidation become final and binding by the defendant itself.

3. 3. Conclusion obtained from the subject Judicial Precedent

 If the defendant had filed a litigation for rescinding the trial decision to avoid that the decision of rejection in the trial for invalidation become final and binding, defendant contention would not have been condemned in the second instance in accordance with prohibition of double jeopardy (Patent Act Article 167) and violation of the principle of faith and trust (the Code of Civil Procedure, Article 2). Therefore, once a defendant of infringement proceedings files a request of a trail for invalidation, it is required to have a decision of invalidation become final and binding or not to have a trial decision of being inadmissible become final and binding until infringement proceedings have been concluded unless a defendant runs out of measures to appeal.

4. 4. Summary

 As described above, it is possible to take double track of both an invalidity defense in infringement proceedings and a request of a trail for invalidation in the patent system in Japan and the double track tends to be a little more popular. Also, it appears that adopting the double track strategy gives a defendant an advantage since a patent owner cannot execute its right unless both decisions in district court and a trial for invalidation were given in favor of the patent owner. However, since an erroneous strategy might cause a fatal result, we, patent attorneys are required to choose and decide to take an appropriate strategy of proceedings according to cases through a relevant communication with our clients.