IP High Court, 2024 (Ne) 10026 — Thermoplastic Resin Composition: Rounding and Equivalents (Miyasaka)
Updated: 3 hours ago
Article information
Article type: Case note
Categories: Patents
Topics: Numerical limitations and parameters, Doctrine of equivalents, Claim interpretation
First published on this website: 2026-10-16
Display and classification checked: 2026-10-17
Case information: 2024 (Ne) 10026
IP High Court, 2024 (Ne) 10026 — Thermoplastic Resin Composition (Miyasaka)
Numerical rounding and the doctrine of equivalents
The issue was whether the appellee’s product, with a molecular weight of 699.91848, satisfied the numerical limitation of a molecular weight of “700 or more.”
⇒ Ultimately, because the applicant had “deliberately” drawn the line at the integer “700 or more,” a rounding argument could not be used. The fifth requirement of the doctrine of equivalents also failed, because the applicant had objectively and externally acknowledged the exclusion of values below that line from the technical scope.
On this reasoning, if the claim had said “700.0 or more,” would a value of 699.95 or more have satisfied it through rounding?
Would it be better to write “7.00 × 10^2 or more” to make clear that the number has three significant digits, rather than being an integer? Certainly, patents are not exactly the same as science: this is a matter of construing the wording of the claims. A neatly rounded “700” may therefore not be the same as “7.00 × 10^2 or more.”
However, “molecular weight” is a value inherent in a substance, without measurement variation, so the patented invention at issue may not have been of a type suited to a rounding argument.
In any event, because numerical equivalents end up failing the fifth requirement, a rounding argument probably still has more potential for numerical values than the doctrine of equivalents, as in earlier cases.
That said, considering predictability for third parties, patents do not permit either rounding or equivalents to be interpreted as flexibly as in science. The conclusion of this judgment may therefore be appropriate.
* This resonates with Osaka District Court, 2002 (Wa) 10511, which, in rejecting a measurement-error argument, held: “Quite apart from the number of significant digits, where ‘3 microns’ is claimed as the upper limit of the technical scope on the basis of the examples, it is questionable to regard the maximum range of error in the examples as falling within the scope of the right. This is because, if there is an error of 0.5 microns in the examples, the claims could state an upper limit covering that error, namely ‘less than 3.5 microns.’ Yet, without doing so, to state the upper limit in the claims as ‘3 microns’ while asserting that ‘less than 3.5 microns’ is the technical scope would impair the clarity of the claims.”
… Of course, it only becomes apparent upon reading the judgment that this should have been done, so it is harsh on the patentee in that particular case. Nevertheless, we practitioners should draft claims for future applications with this judgment in mind.
★ Conclusion: “Numerical values (ranges) in science differ from numerical values (ranges) in patents!!”
(Excerpts from the judgment in 2024 (Ne) 10026)
① Literal satisfaction (rounding argument) ⇒ Not satisfied
“The numerical range of ‘700 or more’ (for the molecular weight of the ultraviolet absorber) at issue here was set by the right holder (applicant) itself to define the scope of its rights. It is nothing other than a boundary dividing, by a single line, what falls within the technical scope of the patented invention (the scope of the monopoly) from what does not. Accordingly, ‘700,’ the lower limit of that range, should be construed as an integer in its original sense, with neither a fractional part that has been rounded down nor a fractional part that has been rounded up. If a different meaning or role is intended for the numerical range, the claims or specification should explain the method of calculating molecular weight, the treatment of decimal values, and similar matters. As stated above, the specification and other documents at issue contain no such description. Consequently, the claim limitation ‘a molecular weight of 700 or more’ must be construed as not being satisfied (and the technical scope as not being met) if the molecular weight is below 700 by even 0.00001.”
② Doctrine of equivalents: first requirement satisfied, but fifth requirement not satisfied
“The numerical range has no critical significance. The molecular weight having technical significance in relation to the functions and effects of the inventions at issue is considered to extend across a fairly broad range, rather than being precisely 700. It is therefore understood that the numerical limitation of ‘700 or more’ was adopted as, so to speak, a ‘round number.’ … It is difficult to consider that the properties as an ultraviolet absorber differ substantially between a molecular weight of 699.91848 and one of 700. … Accordingly, the difference in molecular weight cannot be regarded as relating to an essential part of the inventions at issue. The first requirement of the doctrine of equivalents is satisfied in this case.”
“The integer value ‘700 or more’ was deliberately used, and no critical significance is recognized in the molecular-weight value of 700. That value can therefore be said to have been selected and set, so to speak, arbitrarily by the appellant. Furthermore, the appellant could easily have set the numerical range as ‘699.5 or more’ or specified how decimal values of molecular weight were to be treated, but deliberately took neither measure. This presupposes not only an understanding that decimal values are not technically meaningful numbers, but also that they have no particular legal implications (are not given any special meaning). Thus, by specifying in the claims the molecular-weight range of ‘700 or more,’ the appellant defined the technical scope of the patented invention by the dividing line between ‘700 or more’ and ‘less than 700.’ It is appropriate to find that the appellant objectively and externally acknowledged that substances with molecular weights even slightly below the lower limit of ‘700’ were excluded from the technical scope. The fifth requirement of the doctrine of equivalents is therefore not satisfied.”
* The first-instance judgment, Osaka District Court, 2022 (Wa) 9521, had also rejected the first requirement of the doctrine of equivalents, holding that “where setting a numerical value has significance for the invention, absent special circumstances, the limitation of the technical scope by that numerical value constitutes an essential part of the patented invention.”
Originally published: 2025-03-09
Original Japanese post: https://ameblo.jp/hideki-takaishi/entry-12889274205.html
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2026-10-16: The AMEBLO source was first published on this website.
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