In my previous post, I wrote about an IP High Court judgment (the Maxacalcitol case) regarding doctrine of equivalents in patent infringements in Japan. The defendants appealed against the IP High Court judgment and the Supreme Court handed down the final judgment on 24th March, 2017.
Case Law (Ball Spline Bearing case)
The first affirmative judgment based on the doctrine of equivalents under Japanese patent law was the Ball Spline Bearing case of the Supreme Court in 1998, in which the court established five requirements (See “Further information” at the end) for infringement under the doctrine of equivalents. However, it should be noted that there are very few cases where Japanese courts have affirmed infringement based on the doctrine of equivalents. It has been reported that the first and the fifth requirements of the doctrine of equivalents were the main reasons of dismissal. With regard to the first requirement (so-called “Non-essential part” requirement), a differing part in the claim from the allegedly infringing product/process shall not be an essential part of the patented invention. With regard to the fifth requirement (so-called “No special circumstance” requirement), there shall be no special circumstance such as the prosecution history estoppel in which the allegedly infringing product/process is intentionally excluded from the scope of the claim during the prosecution history by the patentee.
The IP High Court judgment in Maxalcitol case and the issue at the Supreme Court (the fifth requirement)
The IP High Court relaxed its traditional strict interpretation of the first requirement (“Non-essential part” requirement). It held that if the patented invention makes a significant contribution over the prior art, it would be much easier to be protected under the doctrine of equivalents. The defendants didn’t argue this issue at the Supreme Court. What is more important in this topic is that the Court also gave new interpretation on the fifth requirement (“no special circumstance” requirement). The defendants mainly argued at the Supreme Court that this interpretation is too advantageous to the patentee. The issue before the Supreme Court is whether or not the fifth requirement (“no special circumstance” requirement) is fulfilled in this case.
If you want to know more about the IP High Court judgment, please refer to my academic paper (See the footnote).
The patented invention is about a process to manufacture a drug component. In the claim, the patentee clearly defined a “cis” isomer as a starting material of the process. The allegedly infringing process (defendants’ process) is clearly out of the literal scope of the claim because they use a “trans” isomer as a starting material, which has the different steric molecular structure. However, the patentee argued a patent infringement under the doctrine of equivalents because the difference between patented process and defendants’ process is so minor.
The defendants’ argument is as follows. Their process (“trans” isomer as a starting material) could have been easily conceived by the patentee at the filling date, and accordingly their process could also have been easily included in the scope of the claim. Nevertheless, the patentee actually didn’t include their process in the scope of the claim. This way of claim drafting should be recognized as an intentional exclusion of defendants’ process; i.e. there is a “special circumstance”. Therefore, the fifth requirement (“no special circumstance” requirement) should not be fulfilled in this case.
The Supreme Court Judgment
The Supreme Court upheld the IP High Court judgment in this regard. The Supreme Court held that even if the allegedly infringing product/process could have been easily conceived at the filling date, and the applicant didn’t actually include it in the scope of a claim, that fact as such shall not be interpreted as a “special circumstance”. However, if the applicant is considered, objectively or externally, to have recognized that one feature of the allegedly infringing product/process can be replaced into the corresponding feature of the claim, and intentionally haven’t included it in the claim, it shall be interpreted as an “special circumstance”.
The starting material of the patented process is a “cis” isomer, while that of the defendants’ process is a “trans” isomer. Point is that there is no mention on a “trans” isomer in the description of the patent at issue. Therefore, the Supreme Court concluded that the patentee didn’t intentionally exclude a “trans” isomer from the scope of the claim. This interpretation on the fifth requirement is advantageous to the patentee because it works for expanding the applicability of the doctrine of equivalents. After the Maxacalcitol case, it is very likely that the doctrine of equivalents will be affirmed more often.
Further information: The five requirements of the doctrine of equivalents in Japan
The followings are the five requirements in the Ball Spline Bearing case, which have subsequently been followed in later case law.
Even if there is a differing part in the claim (hereinafter referred as “the Difference” or “the Different Part”) from the allegedly infringing product/process (hereinafter referred simply as “the Product”), it is valid to consider that “the Product” constitutes an infringement under the doctrine of equivalents in case the following five requirements are satisfied:
(1) Non-essential part
“The Difference” is not an essential part of the patented invention.
(2) Possibility of interchangeability
Even when “the Different Part” is interchanged by the corresponding part of “the Product”, it could achieve the purpose of the patented invention, and would produce the same function and same effect with the patented invention.
(3) Ease of interchangeability
The person in the ordinary skill in the art could easily come up with the idea of changing “the Different Part” with the corresponding part of “the Product” at the time “the Product” was manufactured/used.
(4) Not part of the prior art
“The Product” is neither identical to nor obvious from the prior art at the priority date of the patent application.
(5) No special circumstance
There is no special circumstance such as the estoppel in which “the Product” is intentionally excluded from the scope of the claim during the prosecution history by the patentee.
Hirotaka Nonaka, “Maxacalcitol”, International Review of Intellectual Property and Competition Law (IIC), December 2016, Volume 47, Issue 8, pp 982–985.