Restriction on Assertions in Retrial of a Court Judgment in Patent Infringement Lawsuit

There is no system for post-grant opposition under Japan’s current effective patent law, but after a patent is granted, a trial may be demanded for the invalidation of the patent by anyone (Article 123(1)(2) of the Patent Act).
 
Invalidation trial may be requested soon after the grant and even after the expiration of patent (but there are some statutes of limitations).
 
There is no threshold for initiating the invalidation trial as long as the formalities are met. The grounds for requesting invalidation trial are not limited to questions of novelty and/or inventive steps. The exceptions are that only a person who has a right to obtain a patent may request an invalidation trial with the grounds that the patent has been granted to a person who does not have a right to obtain a patent and that only a person who should have been listed as a co-applicant may request an invalidation trial with the grounds that the patent has been granted to a patent application that does not meet the requirement of co-applicant.
 
The evidence is not limited to patents or printed publications. The trial board may also examine necessary evidence upon request or ex officio.
 
Typical scenario of invalidation trial and infringement suit is as follows.  
 
A patentee finds a potential infringer and sends a “love letter” requesting that he stop making the patented product. The potential infringer answers that his product is outside the scope of patent claims and/or the patent is invalid. The patentee then brings a law suit at the Tokyo District Court or Osaka District Court. The potential infringer in tern files an invalidation trial at the JPO. In the law suit, the defendant may argue that the patent should be judged as invalid in an invalidation trial. The court may judge the validity of the claims by themselves (the Tokyo District Court and Osaka District Court have special fulltime staffs that help judges. They are mostly patent attorneys and ex-JPO examiners). In the invalidation trial, the patentee may request correction of patent in order to remove deficiencies. Then, the JPO trial board and the Court reach to their decisions independently. It is not rare that the JPO and the Court reach different conclusions. Let us assume that the patentee won at the JPO invalidation trial and the defendant won in the infringement law suit at the Tokyo District Court. The both parties will appeal to the Intellectual Property High Court. The IP High Court will join the two proceedings ((i) Litigation Rescinding the Trial Decision; and (ii) Infringement Court of Second Instance) as much as possible.
 
Let us assume that IP High Court holds that the claims are invalid and therefore there is no infringement. The patentee can file a final appeal to the Supreme Court. But, the Supreme Court will dismiss the case unless it involves a very important matter of law. The patentee has finally lost the infringement case. The case of invalidation trial is remanded to the JPO, and the JPO appeal board who is bound by the court decision will decide that the claims are invalid. Then, the patentee may request a Correction Trial at the JPO in order to remove the defects of the patent. In most cases, the patentee amends the claims to narrow the scope. Under current Japanese Patent Act, with these valid claims, the patentee may request a retrial of the infringement case which the patentee has lost a few years before. The battle continues.
 
Let us now assume that IP High Court holds that the claims are valid and there is an infringement. The defendant files a final appeal to the Supreme Court but the appeal is dismissed. The defendant has finally lost the case. Then, the defendant newly finds a publication that negates the inventive steps of the patented invention. The defendant requests a new invalidation trial, and finally invalidates the relevant claims of the patent. Under current Japanese Patent Act, the defendant may request a retrial of the infringement case which the defendant has lost several years before. The battle continues.
 
Under new Japanese Patent Act, effective on April 1, 2012, neither the patentee nor defendant may request a retrial of the infringement case on the grounds that the patent has been corrected or invalidated afterwards. Ratio legis of this amendment is that if the patentee or defendant may correct or invalidate the patent now, they should have so argued in the infringement law suit years before.
 
I suppose that ratio legis of the “substantial new question of patentability” threshold standard in the U.S. is that the requester of the inter partes review should not abuse the system in order to delay the settlement of dispute. It is interesting to note that the U.S. and Japan take quite different approaches to the same problem of the rapidness of the proceedings.