On December 27, 2013, the Intellectual Property high court rendered a decision, numbered Heisei 25 (Ne) No. 10002, regarding doctrine of equivalents using the basis sentenced by the Supreme Court in 1998.
The first decision by the Supreme Court regarding doctrine of equivalents (The Ball Spline Bearing case), at present, makes up the basis of the doctrine of equivalents in courts in Japan.
In the Ball Spline Bearing case, the Supreme Court ruled that, even if the subject matters in the claim includes “a different portion” relative to the subject article in dispute, the subject article is considered to fall within the scope of the claimed invention if:
1. the “different portion” is not essential,
2. the object of the invention can be achieved and the same effect can be obtained even when the “different portion” is replaced with that in the subject article,
3. the skilled person can easily conceive the replacement at the time when the subject article was produced,
4. the subject article is not identical to known art or is not obvious from the known art before the application of the patent, and
5. the subject article was not intentionally excluded from the scope of the invention during prosecution of the patent.
The above subject case regarded a damage suit between Daio Paper, patentee of Japanese Patent No. 4,197,179 titled “Disposable Dipper” and an infringer, Unicharm producing and selling a disposable diaper.
Claim 1 of the Patent is as follows (labels of the subject matters are added):
A) A disposable diaper provided with a waist opening and left and right leg opening in use,
wherein a girth portion comprising a waist portion including said waist opening and a lower waist portion between the lower edge of said waist portion and the starting edge of said leg opening, is provided with a plurality of extendable members circumferentially located with a space therebetween in a lateral direction,
said disposable diaper further having a half-rigid absorption core extending along the lateral direction to said lower hip portion,
characterized in that
B) said extendable members are located within a range above 60% of the length of said girth portion, said space being below 7.0mm,
C) said extendable members of said lower waist portion are located at the left and right side portions besides the central portion,
D) wherein the extensional stress and the cross-section outer diameter of said extendable members located in said lower hip portion are smaller than the extensional stress and the cross-section outer diameter of said extendable members located in said waist portion and the thickness is below 620 tex and the elongation rate is 150-300%.
The above subject matter C) defining the location of the extendable members was introduced to claim 1 during prosecution, i.e. the patentee voluntary limited the particular location of the extendable members during prosecution.
The difference between the subject article and the claimed invention was that an extendable member of the subject article was located at the left and right side as well as the central portion. Since the subject article did not fulfill subject matters A to D, especially subject matter C of the claimed invention, the subject article did not literally fall within the scope of the claimed invention.
Hence, the main issue in the case was whether the subject article was equivalent to the claimed invention regardless of the difference in subject matter C.
In the decision, the court decided that the subject article is not equivalent to the claimed invention since the subject article was intentionally removed from the scope of the invention during prosecution of the patent and thus does not fulfill the fifth requirement of the doctrine of equivalence. As explained above, subject matter C was introduced to claim 1 during prosecution. Taking the event into consideration, the court decided that the subject article, which has the extendable members in the center of the waist portion, was excluded by the amendment of adding the phrase of “besides the central portion” to claim 1.