September, 2018｜News Letter

1. How should “an Average Molecular Weight” Defined in Claims be Interpreted?

Rohto Pharmaceutical Co., Ltd. v. Y (Individual), Case No. 2017 (Gyo-Ke) 10210 (Decision rendered on September 6, 2018)

The Patentee, Rohto, obtained a patent relating to a refreshing composition for ophthalmology in 2013. Against the Rohto’s patent, an individual, Y, filed an invalidation trial with the JPO in 2015. The JPO dismissed the Y’s demand (JPO’s 1^st decision), and Y filed an appeal against the JPO's 1^st decision to the IPHC in 2017. The IPHC cancelled the JPO's 1^st decision, which was made final and binding. The case was remanded to the JPO, and Rohto demanded a correction of claims. The JPO admitted the correction, but rendered a decision of invalidation on the grounds of not satisfying clarity requirement (JPO’s 2^nd decision). Rohto filed an appeal against the JPO's 2^nd decision to the IPHC in 2017.

The corrected Claim 1 of the Rohto’s patent at issue claims as follows:
A refreshing composition for ophthalmology for imparting the refrigerant when the soft contact lenses are worn, containing:
a) 0.01 to 0.1w/v% of a compound selected from menthol, camphor and borneol in total,
b) 0.01 to 10 w/v% of at least one selected from potassium chloride, calcium chloride, sodium chloride, sodium hydrogen carbonate, magnesium sulfate, disodium dihydrogen phosphate, sodium dihydrogen phosphate, sodium dihydrogen potassium, and
c) 0.001 to 10 w/v % of a chondroitin sulfate having an average molecular weight of 20,000 to 40,000 or a salt thereof;
on the proviso that a composition containing a regional anesthetic is excluded.

One of the main issues in this case related to what specific average molecular weight should be meant by “an average molecular weight” defined in the claims. The IPHC answered to the issue as follows:

In the JPO’s decision, the JPO decided that it was unclear what was specifically meant by “an average molecular weight” defined in the corrected Claim 1 even by reasonably interpreting it on the basis of common technical knowledge, and thus that the corrected Claim 1 did not satisfy the clarity requirement.

However, the IPHC overturned the above JPO’s decision as below:

First, the IPHC found that there was no description in the specification of the patent application at issue clarifying whether the “average molecular weight” mentioned in “chondroitin sulfate having an average molecular weight of 20,000 to 40,000 or a salt thereof” defined in the corrected Claims means weight average molecular weight, viscosity average molecular weight, number average molecular weight or others.
Nevertheless, the IPHC ruled that even in such a case, when it was possible to reasonably infer what the average molecular weight was by reasonably interpreting the descriptions regarding the chondroitin sulfate or a salt thereof and other polymer compounds mentioned in the specification and by considering common technical knowledge of those skilled in the art, the term should be interpreted as such.

On the basis of the above ruling, the IPHC reviewed the specification and the common technical knowledge in detail, and found as stated below:

The specification discloses that: The chondroitin sulfate or a salt thereof used in the present invention was a well-known polymer compound, and one having an average molecular weight of 5,000 to 500,000 was used. Chondroitin sulfate or a salt thereof having an average molecular weight of more preferably 5,000 to 500,000, still more preferably 5,000 to 100,000, and particularly preferably 5,000 to 40,000 was used. Commercially available chondroitin sulfate or a salt thereof might be used, for example, sodium chondroitin sulfate marketed by Seikagaku Corporation (having an average molecular weight of about 10,000, average molecular weight of about 20,000 or average molecular weight of about 40,000 and others). (See paragraph [0021].)
Regarding the above mentioned “sodium chondroitin sulfate marketed by Seikagaku Corporation (having an average molecular weight of about 10,000, average molecular weight of about 20,000 or average molecular weight of about 40,000 and others)”, as of the date of filing the present application, Seikagaku Corporation provided figures of weight average molecular weight as the average molecular weight of sodium chondroitin sulfate manufactured by them. Considering that figures publicly known to those skilled in the art as the average molecular weight of sodium chondroitin sulfate manufactured by them were figures of weight average molecular weight, it could be reasonably understood that the “average molecular weight” was weight average molecular weight.

In addition, the average molecular weight of other polymer compounds disclosed in paragraphs preceding the above mentioned paragraph of the specification reasonably be understood to be the weight average molecular weight; and it was common technical knowledge as of the date of filing the present application that the average molecular weight of polymer compounds was generally expressed by the weight average molecular weight. These factors could be sufficient grounds to support the above conclusion that the average molecular weight mentioned in “chondroitin sulfate having an average molecular weight of 20,000 to 40,000 or a salt thereof” defined in the corrected Claims was the weight average molecular weight.

On the basis of the above findings, the IPHC decided that the average molecular weight mentioned in “chondroitin sulfate having an average molecular weight of 20,000 to 40,000 or a salt thereof” defined in the corrected Claims could also be inferred to mean weight average molecular weight.

Conclusively, the IPHC upheld the Rohto’s appeal, and cancelled the JPO’s decision.

An appeal to the Supreme Court was NOT filed against this decision, and thus the decision is final and binding.

K&P’s Comments An interpretation of an average molecular weight has been repeatedly argued in courts, and courts often did not admit that it was clear when the average molecular weight was not specifically defined, such as a number average, weight average, viscosity average or others.
Although this IPHC decision admitted that it was clear, it is strongly recommended that the average molecular weight be specifically defined and the measurement method thereof as well in order to avoid such an argument made in the above case.

(by Katsumasa OSAKI, Patent Attorney)

In September 2018, the IPHC handed down 24 decisions including the above case on patent, and overturned the previous decisions in 4 cases.

In August 2018, the IPHC handed down 6 decisions on trademark, and maintained all the previous decisions.

In August 2018, the IPHC handed down no decisions on industrial design.