The strategies for patent litigation under the double track system in Japan

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In my previous posting (here), I described advantages and problems in the two systems, i.e., the double track system and the bifurcation system in patent litigation. In this posting, I, as a Japanese patent litigator, would like to introduce several practical strategies for patent litigations under the double track system in Japan in the form of Q&A.

Q1. Is it advantageous for a defendant in an infringement proceeding to initiate an invalidation proceeding at the Japanese Patent Office in addition to an invalidity defense in an infringement proceeding?

A1. Yes, it is fairly advantageous. Generally speaking, disputing on patent invalidity in both proceedings is highly recommended if a defendant manages the costs for patent attorneys and lawyers. Although the cost for agents might become almost twice compared to a single proceeding, it would be truly worthwhile. There are two reasons for that. First, a defendant would be able to win the patent litigation only if he succeeds in invalidating the patent at issue either in an infringement proceeding (invalidity defense), or in an invalidity proceeding, causing him to obtain double opportunities to win the patent litigation. Second, a defendant could increase the chance to receive a benefit of file wrapper estoppel. If a patentee asserts something inconsistent in an invalidation proceeding, a defendant could pick it up and use it in an infringement proceeding (See Q3).

Q2. When should a defendant in an infringement proceeding initiate an invalidation proceeding at the Japanese Patent Office?

A2. He should file it soon after a promising ground is prepared. Once a judgment of an infringement court in favor of a patentee becomes final, a defendant is not allowed to file for a retrial even if the patent at issue, later on, turns out to be invalid in an invalidation proceeding at the Japanese Patent Office (Art. 104 quater of Japanese Patent Act). Considering that the average period for infringement litigations at first instance is reported to be getting shorter (approximately 12 months), a defendant should initiate an invalidation proceeding, together with an invalidity defense in an infringement proceeding, soon after strongly relevant prior art is found. An infringement court has discretion as to stay a proceeding based on the parties’ petition (Art. 168 (2) of the Japanese Patent Act). But a defendant can’t expect the court to always stay because the court will do so only when it is really necessary.

Q3. What could be the most important point to be noted for a patentee to deal with in the double track system?

A3. A patentee must be extremely careful about a file wrapper estoppel. In an infringement litigation, especially when novelty and inventive step are disputed, a patentee finds himself in an uncomfortable situation between offense and defense, in which he has to assert that the scope of the patent could be broadly interpreted to cover the defendant’s product/process (offense), whereas he has to assert that it should be narrowly interpreted to meet the requirements for patentability over those prior arts (defense). In many cases, a duplicity brings serious disadvantage to a patentee, which is known as a file wrapper estoppel. Therefore, a patentee must be consistent in both proceedings.

Q4. In what kind of proceeding could a patentee’s assertions be taken into account as a file wrapper estoppel in an infringement proceeding?

A4. All patentee’s relevant assertions in all relevant proceedings could be taken into account in an infringement proceeding including the assertions during a patent examination, an opposition proceeding, an invalidity proceeding, an invalidity defense, and even those with regard to a divisional patent application. What a patentee has to pay considerable attention is the assertions made by himself in an invalidity proceeding because a patentee usually focuses only on defense in an invalidity proceeding, forgetting that a negative effect which the assertion could bring about in an infringement proceeding. In order to be entirely consistent, one tip is to organize a single team for both proceedings and let just one drafter prepare the documents to be filed to ensure consistency.

Q5. Could an assertion be taken into account as a file wrapper estoppel even if it didn’t actually contribute to maintain the patent?

A5. No, it basically couldn’t. Although further case law is to be expected, there is one district court judgment, in which it was held that a file wrapper estoppel shouldn’t be applied in the case where the amendment didn’t contribute to maintain the patent at issue. Accordingly, it is true that not all assertions made by a patentee is taken into account as a file wrapper estoppel. However, it is noted that a patentee, on the safe side, should always be consistent without expecting this particular lower court judgment to be applied to his statements if they are inconsistent.


Hirotaka Nonaka

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