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Is numeral range limitation specifying either upper limit or lower limit always unclear?

Claims are required to be clearly recited. If claim language is determined unclear, it may lead to a situation where an application is refused, a patent is cancelled, or a patent is invalidated. In practice, some claims include a numerical range limitation. In order to ensure the clarity of a claim with such numerical range limitation, it is considered preferable to clearly define both limits, i.e., an upper limit and a lower limit.
However, it is not always practically possible to define a numerical range limitation using both an upper limit and a lower limit, and there may be cases where the numerical range limitation has to be defined by either the upper limit or the lower limit. In addition, there are not a few patents including a claim with a numerical range limitation defined by either an upper limit or a lower limit.
The Intellectual Property High Court recently made a decision (2019 (Gyo Ke) No. 10041) that a claim with a numerical range limitation defined only by a lower limit (absence of an upper limit) was not unclear. We will introduce this case hereinafter.


Clarity requirements


Patent Law Article 36 (6) (ii) specifies, as one of the requirements to be satisfied by a claim recitation, that “the invention for which a patent is sought is clear”. In other words, Patent Law Article 36 (6) (ii) specifies clarity requirements. This clarity requirements are included not only in the reasons for rejection (Patent Law Article 49 (iv)), but also the reasons for opposition (Patent Law Article 113 (iv)) and the reasons for invalidation (Patent Law Article 123 (iv)).
The Japan Patent Office (JPO) publicizes “Examination Guidelines for Patents and Utility Models”, which states five types of violation of the clarity requirements. One of them is “(5) the case where a claim includes an expression which may make the scope of an invention ambiguous, and as a result, the scope of the invention is unclear”. One of the examples of this case is given as “expressions using a numerical limitation which only indicates either an upper limit or a lower limit such as ‘not less than…’ or ‘not greater than …’” (Examination Guidelines for Patents and Utility Models, Part II, Chapter 2, Section 3, Clarity requirements, 2.2 (5) (b)).
However, the Examination Guidelines also state that “even if a claim includes an expression where the scope cannot be identified, an examiner shall not immediately determine that the scope of the invention is unclear, but consider whether the scope of the invention can be understood by considering the statements of the description and drawings as well as common technical knowledge as of the filing”. The Examination Guidelines mention that there may be cases where a numerical range limitation that indicates either an upper limit or a lower limit is not necessarily determined to be unclear.


Judgment of the Intellectual Property High Court
(2019 (Gyo Ke) No. 10041, Date of Judgment: February 4, 2021)

(1) Outline
“2019 (Gyo Ke) No. 10041” was a case in which the validity of Patent No. 543762 titled “Surface Sheet for Wound Dressing Material and Wound Dressing Material” was tried in court.
In this case, inventive step and support requirements were also tried in addition to the clarity requirements. This article will focus on the judgement in terms of the clarity requirements.


(2) Determination of Clarity
Claim 1 of this patent relates to a wound dressing material, and is described as follows.
[Claim 1] (underlined portions are amended recitations)
A wound dressing material comprising:
at least two layers of a liquid permeable layer (1) and an absorbent retaining layer (3),
wherein the liquid permeable layer (1) and the absorbent retaining layer (3) are directly laminated sequentially in this order from a side where a wound site (15) is faced when in use,
wherein the liquid permeable layer (1) includes a first surface (11) facing the wound site (15), a second surface (12) opposite the first surface (11), and through holes (13) penetrating through the two surfaces (11,12) in a thickness direction,
wherein a rate of hole area of the through holes (13) is 3.07% or more and the through holes (13) allow liquid to pass from the first surface (11) to the second surface (12),
wherein the first surface (11) is formed of a hydrophobic resin sheet material,
wherein the absorbent retaining layer (3) includes a sheet material capable of absorbing and retaining water,
wherein the absorbent retaining layer (3) is not integrated with the liquid permeable layer (1),
wherein the through holes (13) each have a depth of 100 to 2000 μm, and
wherein the through holes (13) exist at a density of 50 to 400 per square centimeters.


(Course of Events)
With respect to the recitation of “a rate of hole area of the through holes (13) is 3.07% or more” in claim 1, in a trial for patent invalidation, a trial decision was made that “the invention cannot be said to be unclear only because the upper limit of the rate of hole area is not defined, and the scope of the claim conforms to the requirements set forth in Patent Law Article 36 (6) (ii) (hereinafter referred to as ‘clarity requirements’). Therefore, Invalidation Reason 4 in which the plaintiff claims the violation of the same paragraph has no grounds”.
The plaintiff suited for canceling the trial decision on the grounds that the rate of hole area is a feature directly related to the problems to be solved by the invention, and the insufficient definition of the rate of hole deprives of the predictability regarding the scope of the exclusive right of the patent right.
In this regard, the Intellectual Property High Court made a determination of the trial decision as follows.

“The recitation of ‘a rate of hole area is 3.07% or more’ itself is clear, and even if an upper limit of the rate of hole area is not defined, it is clear for a person skilled in the art that this configuration does not include a rate of hole area in which holes are practically unable to exist as holes. Therefore, it cannot be said that the lack of the definition of the upper limit of the rate of hole area deprives of the predictability of the scope of the exclusive right of the patent right.”


(Consideration)
In this way, in this judgment, even if the claim does not define the upper limit of the numerical range of the rate of hole area, the claim was not determined unclear since a person skilled in the art clearly understand that the configuration of the rate of hole area does not include a configuration in which holes are practically unable to exist as holes.
However, based solely on this judgement, it may be difficult to make a general determination on which case a claim recitation is considered obvious/clear for a person skilled in the art even in the absence of either an upper limit or a lower limit of a numerical range. Therefore, in the following section, we would like to review general criteria of courts regarding the clarity requirements.


General Criteria of Judgment by Courts on Clarity requirements


As understood from several court judgements (e.g., 2018 (Gyo Ke) No. 10117, 2009 (Gyo Ke) No. 10434, and 2014 (Gyo Ke) No. 10254), the following three criteria for the clarity requirements are generally adopted by the courts.


(i) Criterion 1
“The clarity of the invention for which a patent is sought should be judged not only based on the statement of the claims, but also based on common technical knowledge as of the filing, in consideration of the statement of the specification and drawings attached to the application”. This criterion is similar to the descriptions of the JPO's Examination Guidelines for Patents and Utility Models mentioned above.


(ii) Criterion 2
"The judgement should be made in terms of whether or not a claim recitation is unclear enough to unduly harm interests of a third party.”


(iii) Criterion 3
“The clarity requirements are judged based on whether or not the technical scope of the patent that the applicant seeks to obtain by the application is clear, not based on whether the technical scope is sufficient as a configuration or a method to solve the problems to be solved by the invention.”


Summary


When making a claim that includes a numerical range limitation, it is preferable to define both an upper limit and a lower limit of the numerical range. In this case and especially in a case where the numeral range is defined by either the upper limit or the lower limit, it is recommended to confirm that the invention of the claim is clear in light of Examination Guidelines for Patents and Utility Models and the above-mentioned Criteria 1-3.
In addition, when attacking or defending a patent that includes a claim with a numerical range defined by either an upper limit or a lower limit, it is also advantageous to develop strategies in full consideration of Examination Guidelines for Patents and Utility Models and the above-mentioned Criteria 1-3.
In this article, we have introduced judgments on the clarity requirements for claims including a numerical range defined by either an upper limit or a lower limit. We would like to shortly introduce judgements and criteria of similar cases in terms of support requirements, enablement requirements, and inventive step.


Edited by Seiji Kimura

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