treatise

I. Introduction

The Supreme Court decision in the Ball Spline Bearing Case approved the application of the doctrine of equivalents and outlined its requirements. In Japan, will this doctrine, now endorsed by the courts, be considered when determining the scope of all patent rights?

The manner in which patent claims are drafted varies widely, and the technical concepts used to limit the elements of an invention in patent claims also vary in scope. Regardless of the type or scope of the limiting concepts used to define the elements of a patent invention, does the doctrine of equivalents apply to all patent inventions? In particular, how does it apply to patent inventions involving functional expression claims?

With the amendment of Article 36, Paragraph 6 of the Patent Act in 1994, the permissibility of describing the structure of an invention in functional terms has expanded. However, it is not uncommon to use functional expressions to draft claims in order to avoid unnecessary limitations as much as possible. It is expected that more such claims will be granted patent rights in the future, and it is also natural to anticipate the occurrence of patent infringement cases involving such functional expression claims.

Against this backdrop, we will examine the scope of patent rights for functional expression claims, starting with the question of whether the doctrine of equivalents can be applied to functional expression claims, as indicated in the subtitle.

2. The Significance of the Scope of Functional Expression Claims

A “functional expression claim” refers to a patent claim in which the elements of an invention are expressed in terms of their functions. However, it is essential to clarify what is meant by “function” in this context, as failure to do so could result in inconsistencies in the basis for examination.

Concepts similar to “function” include ‘action’ and “effect.” These correspond superficially to terms such as “function,” “operation,” and “effect or result” in the United States. Additionally, the three elements established as criteria for applying the doctrine of equivalents in the Graver Tank case, a leading case on the doctrine of equivalents in the United States, are “function,” “way,” and “result.”When considering the meaning of “function” in relation to the foreign term “equivalence doctrine,” it may be necessary to examine its relationship with these elements. However, this paper focuses on the scope of rights of function-based claims in patent applications permitted in Japan, so we will not dwell on the essential meaning of the above English expressions in defining “function.”

That is, “function” refers to “an action that leads to a certain result (effect)” and “something that has the potential to selectively set specific configurations that perform that action.” Therefore, it is a concept that includes both action and effect, and does not specify specific structural elements. The following discussion will proceed based on this meaning.

Therefore, limiting a ‘means’ or “component” by its attributes or properties does not constitute a functional expression as used here.For example, “elastic means” has a certain width and possesses the potential to selectively set specific configurations that correspond to its subordinate concepts. However, “elastic means” merely indicates its attributes and does not indicate any action or result. In other words, while it is a means that possesses elasticity, it does not clearly specify whether it performs a cushioning action or possesses a repulsive action, etc. Therefore, it is not a functional expression.For inventions that have components limited by such attributes or properties, it is considered sufficient to determine the applicability of the equivalents doctrine according to the usual standards and requirements.

A typical example of a functional expression claim is one that includes components expressed in the so-called US “means plus function” format. For example, “a cushioning means” as a means for softening an impact. It is a concept that combines both action and result.

Note that this paper does not specifically address whether the entire invention is functionally expressed, whether it is partially functionally expressed, or whether the essential part of the invention is functionally expressed or non-essential. However, analyzing these cases separately could be one point for consideration.

3. Treatment of functional expression claims in Japan

There are no specific regulations regarding the use of “function” + ‘means’ expressions such as “～～means” to describe the constituent elements of an invention in the scope of a patent claim, and there are no particular disadvantages to doing so. This was also the case prior to the 1994 amendment, which made functional expression claims more widely acceptable, as mentioned above.

Additionally, the “Guidelines for the Application of the 1994 Amendment to the Patent Law and Related Laws” (published by the Japan Institute of Invention and Innovation) (hereinafter referred to as the ‘Guidelines’) lists “clarity of the scope of the invention” as a point to consider when using functional expression claims.For example, if the specific means for achieving the function can be immediately recognized, it is considered clear. This is based on the fact that the Patent Act explicitly states in Article 2, Paragraph 1 that an invention is a “creation of a technical idea,” and thus, in the claims, it is sufficient for the elements to be described to the extent that they can be understood as a “technical idea.”

Furthermore, in the examination stage, the portion of the elements expressed as “function (AA)” + ‘means’ is naturally subject to examination as all means possessing such a “function,” and not only the specific configuration of the embodiment described in the specification is subject to examination.Therefore, even if the configuration described in the embodiment has novelty, if other specific configurations included in the “AA means” or those similar to them are already known (unless there are other distinguishing features), the invention lacks novelty or inventive step. Thus, unless the configuration of the embodiment is reduced, at least novelty is denied.Therefore, if the “AA means” is deemed to satisfy the patent requirements after examination and a patent right is granted, it is naturally understood that the scope of the rights extends to all elements included in the concept of the “AA means.”

4. When the scope of a functional expression claim is considered in a narrowing direction

In the case of a functional expression claim, while it cannot be said that the entire scope of the function is covered by the scope of the claim, if the description is too abstract to clearly grasp the configuration of the invention, i.e., if it has not reached the level where it can be understood as a technical idea, the situation is different.

In such cases, since the core technical idea is not clearly defined, the application of the “equivalent doctrine,” which seeks to establish a broader scope of rights than the literal wording, is inherently difficult. Rather, in such cases, if it is deemed that the technical idea can only be understood from the description in the specification (embodiment), it may be unavoidable to consider narrowing the scope of rights by examining whether there is an infringement based solely on the description in the specification (embodiment).

Examples of case law reflecting this approach include the Ball Bearing Automatic Assembly Machine Case (Tokyo District Court, 1969 (Wa) No. 6127) and the Coin Locker Case (Tokyo District Court, 1975 (Wa) No. 2564).

In the former case, the court held that the “cooperation” between the “measuring means” and the “assembly means” was merely a statement of the problem and was abstract, such that the invention could not be clearly understood from the scope of the claims alone. The court determined whether the invention fell within the technical scope based on the description in the specification (the appellate court also stated that “it is necessary to reasonably interpret and determine what specific technical idea is disclosed from the drawings and the entire specification”).The latter ruling also interpreted the claims as limited to the description in the specification and drawings, citing their overly abstract nature.

The claims at issue in these decisions may be said to define each element of the invention using functional expressions. However, only the functions of each component and the results arising from the invention as a whole are disclosed, and the functions of the components are not linked, so the overall function of the invention is not clear, and the invention cannot be clearly understood from the claims alone.

According to the aforementioned application criteria, even if the meaning of the functions is not clear from the claims themselves, if the claims can be interpreted based on the specification or technical common knowledge to understand the specific objects included in their scope, they are deemed to satisfy Article 36(6)(ii) of the Patent Law (the scope of the invention is clear).If an application with abstract claims like the above case and a single example of implementation is deemed not to violate the current Article 36 under this approach, it is likely that such patents will continue to be granted to some extent in the future. In such cases, it is unavoidable that the scope of rights may be narrowed based on the description in the specification, as the claims are drafted with incomplete functional expressions (the overall function of the invention is not clearly defined).

However, if the functions of the invention are not immediately clear from the claims alone, but can be clearly understood by referring to the specification, such cases differ from those where the technical idea can only be grasped from the specific examples described in the specification. Therefore, the entire scope of the clarified functions should be considered the scope of the patent rights and should not be narrowed based on the specification.

Furthermore, when considering the reduction of the scope of rights based on the description in the specification, one consideration is the extent to which the scope of rights should be recognized based on the specific configuration of the embodiment. This paper focuses on the application of the doctrine of equivalents to function-based claims, so the above consideration regarding cases where the doctrine of equivalents cannot be applied to claims is not addressed here.

5. Scope of claims using functional plus means expressions in the United States

(1) Background of USP Section 112(6)

When a claim is drafted using a means plus function expression for a combination, the provisions of USP Section 112(6) apply.

The historical background of this provision stems from the 1946 Halliburton decision, which held that claims described using means-plus-function language were invalid, leading to an overly stringent (or overly strict) tendency in regulating such claims. To address this tendency, the law was amended in 1952 to permit claims using means-plus-function language and to clarify their treatment.Therefore, the difference in the existence of such provisions is not due to a difference in the concept of invention between Japan (as defined in Article 2, Paragraph 1 of the Patent Act) and the United States.

3. Regarding Article 102, Paragraph 3

(i) This provision recognizes the so-called “equivalent amount of royalties” as the minimum amount of damages that may be claimed, thereby granting patent holders the right to claim such amount as compensation. However, when determining the amount of damages under this provision, it is natural to consider the extent to which the distinctive features of the patented invention contribute to the infringer’s transactions.Of course, the concept of “contribution rate” has been considered in case law (October 29, 2002, Osaka District Court, Case No. Heisei 11 (Wa) 12586, Patent Right “Konjac Manufacturing Method”), and this is an issue that would naturally be considered when determining the actual terms of an implementation agreement, i.e., when the parties decide on the implementation fee. Therefore, even after the word “usual” was deleted from the provision, it is considered that this does not affect the consideration of such matters.In such cases, it is appropriate to determine the “contribution rate” by considering the extent to which the patent invention contributes to the products or profits of both parties.

Additionally, in the aforementioned case involving “Konjac Manufacturing Method,” in addition to calculating the royalty rate, the contribution of the patent invention was examined, and the “contribution rate” of 40% was multiplied by the “royalty rate” of 3% to determine the amount.

As such, since the “contribution rate” is appropriately considered in calculating the royalty equivalent amount under this provision, it is considered that the size of the claim subject matter is not a significant factor in determining the applicability of this provision.

(b) As a reference, we will examine whether something similar to the “contribution rate” in Japan is considered in the calculation based on the so-called “license by estoppel” (presuming that a license was granted for the infringing act) in Germany for the presumption of patent infringement.

This consideration is based on the response provided by Mr. Hans-Peter Staudt (European and German Patent Attorney) to a question posed during an anonymous seminar on October 28, 2005, with his permission, and is excerpted and translated for reference.

In calculating damages under the “license by estoppel” doctrine, particularly when the infringing product is an assembled product, a device combined with other products, or a device constituting part of another product, what constitutes the basis for calculation? In other words, when the patented subject matter is a component part, must the calculation be based on the component part itself or the entire assembled product containing it?For example, if the distinctive feature of the invention is a “seat,” and the infringing product is a passenger vehicle equipped with that “seat,” is the basis for calculation the seat itself or the passenger vehicle?Furthermore, does it make a difference if the claim is described as “a seat used in a passenger car” or “a passenger car having a seat”?

This is, of course, a matter that depends on the specific circumstances of each case, and ultimately the specific circumstances will determine the outcome. However, as summarized below, several principles have been established in German case law.

One of the points to consider is what is considered to be the customary practice in trade and what is considered to be the actual understanding of the industry. For example, it must be determined whether the assembled product is typically traded as a whole or whether the value of the whole is enhanced by the “part” (device) that is the subject of the patent. From another perspective, it must be determined whether the assembled product is specifically characterized by the patented part, i.e., whether the patented part strongly defines the assembled product.Furthermore, the decisive factor is whether the patented part itself is traded in such a way that it can determine (be recognized as determining) the value of that part. If these conditions are not met, only the patented part is generally considered the basis for calculation. In the above example of seats and passenger cars, the “seat” part would be considered the basis for calculation.

The second point is that, assuming the basis for calculation is “seat,” what kind of actual price should be considered for the “seat.” Car seats are typically traded as spare parts or adjustment items after the sale of a passenger car, but they are also traded as part of the assembled product, i.e., the passenger car itself.In this case, two separate prices may be considered. Specifically, the retail wholesale price of each seat when traded on its own and the price of the seat when sold as one of the components of the vehicle should be considered, and the average of these prices would be used.

As described above, when determining the basis for calculating damages under the “implementation license analogy” in Germany, this is not determined based on the scope of the subject matter described in the claims, but rather by examining the relationship between the essential features of the patented invention and the overall context of the actual transactions, as described above.In this way, even in the application of the “license-based analogy” in Germany, the scope of the claims themselves does not directly influence the determination of the amount.

(2) Purpose of USP Section 112(6)

This provision (in its preceding and following paragraphs) functions in at least two directions. On the one hand, it permits the description of claim elements in the means-plus-function format when claiming a combination. On the other hand, it limits the scope of such claims to equivalents of what is described in the specification.

That is, one aspect is to eliminate the burden on the applicant of creating claims that cover all alternatives capable of performing the function by limiting the elements of the invention to their functions alone, and to avoid narrowing the scope of the claims by limiting them to specific configurations. The other aspect is to protect the public interest by limiting the scope of the claims as defined by their wording.

This provision is significant both in examination and in the interpretation of the scope of rights.

(3) Differences from the above Japanese case law

The provision of Section 112(6) of the USP does not apply because the claims described in the means-plus-function format are too abstract to grasp the invention.

There is no requirement that such an invention be unclear, and the provision applies to all claims described in the means-plus-function form. Therefore, the approach taken in the two Japanese cases cited earlier (the Ball Bearing Automatic Assembly Machine Case and the Coin Locker Case) is fundamentally different.In other words, while the two precedents mentioned above resulted in an interpretation that limited the scope of rights based on the description in the specification, which is similar to the content of the provisions of Section 112(6) of the USP, the fundamental reason was that the technical idea could not be clearly understood from the claims alone, and the interpretation was based on the specific content of the examples, which is entirely different.

(4) A different concept from the so-called “equivalent doctrine”

The provisions of Section 112(6) of the USP do not adopt the so-called “equivalent doctrine,” which seeks to recognize rights beyond the scope of the claim based on the claim itself. Instead, they address infringement based on the literal language of the claim and establish a standard for determining “equivalents” with respect to the subject matter described in the examples.

In the United States, where there is more developed case law and discussion regarding the interpretation of the scope of rights based on the scope of claims (equivalence doctrine) compared to Japan, means-plus-function claims, which are functional expression claims, are generally treated in a manner that limits the scope of rights derived directly from the wording (function) itself, regardless of whether the function is clearly defined or not.This is considered to be a useful reference for examining the scope of rights of functional expression claims in Japan.

(5) Comparison between Japan and the United States

Japan does not have a provision similar to Section 112(6) of the USP. In Japan, when an invention involving a combination of multiple components is described in the means-plus-function format, there is no particular problem with the requirements for description in the specification (Patent Law Article 36) as described above.For example, if expressions such as “cushioning means,” “connecting means,” “squeezing means,” “lifting means,” etc., are used, the disclosure requirements are deemed to be satisfied as long as the invention can be clearly understood.

Furthermore, in Japan, even in cases where the invention relates to a single component rather than a combination, it is possible to describe it using functional expression claims as long as the technical idea can be clearly understood.In the United States, such functional expressions for single means are not permitted (U.S. Patent and Trademark Office Patent Examiner’s Manual 706.03(c) → single means claim) (U.S. Patent Practice Dictionary, published by AIPPI JAPAN, 3rd edition, p. 240). Functional expression claims are only permitted when the requirements of the first paragraph of Section 112(6) of the U.S. Patent Code are met (for combinations).

For example, in Japan, if the C element of a patent invention consisting of the components A + B + C + D is described as a “cushioning means,” even if the specification only describes the specific means “spring,” any means having the function of “cushioning” is included within the scope of the claims.

On the other hand, in the United States, if the specification only describes “springs” in the examples, the determination of infringement involves assessing whether the cushioning means of the prior art is equivalent to “springs.” Therefore, while the scope of rights recognized in Japan may be broader than that in the United States, it cannot be narrower.In Japan, while there is a possibility of limitation in special circumstances such as consideration of prior art or intentional exclusion, in principle, all “buffering means” fall within the scope of the rights.

6. Distinction between literal infringement of functional expression claims and the application of the doctrine of equivalents, and identification of issues

The question of whether one of the components of the prior art is included in the “means” of the functional expression of the patented invention is a question of literal infringement, not a question of the application of the doctrine of equivalents.

Additionally, in cases where the functional expression claim cannot be understood solely from the description of the claims, the discussion is in the opposite direction of the doctrine of equivalents (which extends beyond literal infringement).

Therefore, the discussion regarding the doctrine of equivalents in relation to functional expression claims pertains to whether a “BB means” that performs a function different from that of ‘AA’ is included in “AA means,” and whether such inclusion constitutes infringement.

The question that arises here is whether the doctrine of equivalents should be applied so broadly. Considering the application of the doctrine of equivalents to configurations with different functions may seem to contradict the original purpose of the doctrine. However, it is also possible to adopt the view that there is no need to regard this as a particular issue and that the Supreme Court’s criteria should be applied as they are. Even with such an approach, the conclusion may remain the same (ultimately, the criteria for applying the doctrine of equivalents are not met).

However, it cannot be said that there is no connection between the purpose of the doctrine of equivalents, the principles underlying its application, and the manner in which the scope of the patent claims is drafted. Therefore, even if the doctrine of equivalents has been endorsed, it is necessary to consider whether it can be applied directly to all patent claims, especially from the perspective of how claims are drafted.

7. No application of the doctrine of equivalents to functional expression claims

(1) Regarding whether the doctrine of equivalents should be considered for functional expression claims, it is basically necessary to first examine whether it is consistent with the purpose of the Patent Act, social justice, and the principle of equity, which are the purposes of adopting the doctrine of equivalents as indicated in the Supreme Court decision, and in particular whether it is consistent with the principle of equity.

When the functions performed by each element of an invention within the invention as a whole are accurately captured, and the elements are limited by their “functions,” ensuring a broader scope of rights (beyond the literal meaning) would seem to be contrary to equity in the sense of overprotecting the rights holder.In other words, the scope of the claim is inherently defined by a certain degree of flexibility, and since this scope corresponds to the scope of the technical idea to be protected by the invention, protecting the invention within the literal scope of the claim is sufficient to achieve equity.

(2) Consideration in relation to “substitutability,” one of the criteria for the doctrine of equivalents

“Substitutability” generally refers to whether something can be replaced without impairing the identity of its function or effect. However, since functional expression claims are limited by the elements defined by a specified range of functions, the scope for measuring “substitutability,” one of the criteria for the doctrine of equivalents, is already defined by the literal scope of the claims.

Therefore, further examining the requirement of “substitutability” as a criterion to expand this scope is inherently problematic. In other words, since it is impossible to set a scope beyond literal infringement without changing the “function,” the requirement of ‘substitutability’ cannot be satisfied in the first place, and asserting that it is satisfied would be contradictory.

(3) The meaning of “identity of function (action, effect)” in “substitutability”

The configuration of “AA means” inherently involves a specific entity with a certain range of options. Its scope is determined by whether it performs the same function.

In cases where an object of Item (i) appears that possesses the function of “AA” but also possesses other functions in addition to AA, how should such a specific means be treated? Such specific means should be examined as an issue of literal infringement rather than as an issue of the doctrine of equivalents.In other words, even if it possesses other functions, it still possesses the “AA” function, and the effect of the invention (qualitatively identical effect) is achieved. Therefore, such an object should be interpreted as falling within the scope of the common function, i.e., the literal scope.

Thus, even in the case of objects with other functions, it is sufficient to resolve the issue as a literal infringement issue without considering the doctrine of equivalents.

(4) Consideration based on precedents where equivalence was actually examined

1. For example, in the “log peeling machine” case (Asahikawa District Court, 1980 (Wa) No. 61, March 24, 1983), which is cited as an example affirming the scope of equivalence, the scope of the registered claim explicitly states that a “cylinder piston rod” is used as a means for rotating the “arm pestle.”On the other hand, the subject matter of the comparison object uses a “crank mechanism” as the means for rotating the “arm pestle,” but both the ‘substitutability’ and “ease of substitution” requirements were recognized, and it was deemed equivalent. In other words, the scope of the utility model registration claim in this case specified a concrete configuration, “cylinder piston rod,” rather than the “function + means” form, leaving no room for alternative choices.It was not a functional expression claim element that sought to define the scope by the radius of “functional identity.” 

2. In the Tokyo High Court decision in the Ball Spline Case, the limiting features of the elements of the “outer cylinder” include “U-shaped grooves in cross section” and “same depth.”These are also concepts that specifically identify the structure and are not functional expressions. In contrast, the subject matter of Item I has a “semicircular groove” and a “depth of approximately 50 microns,” but the technical significance of both was found to be identical, and they were deemed substantially identical.

3. In the Osaka District Court ruling on the Velcro Fastener Case, Case No. 6444 of 1967 (April 2, 1969), the “hook-stopping member” described in the claims was intended to correspond to multiple loops, whereas the Item I object was a “mushroom-shaped engagement protrusion.”The court recognized the identity of the solution principle (hooking onto loops) and the ease of substitution, thereby deeming it an equivalent means (the High Court reached the opposite conclusion).

 As described above, claims recognized as equivalent in court decisions are not functional expression claims but rather claims whose elements are described in a manner that specifies specific structures or shapes.Here, the court is using a negative rationale to conclude that the doctrine of equivalents does not apply to functional expression claims by relying on the fact that the claims in the aforementioned case, where the doctrine of equivalents was applied, were not in the form of functional expression claims. However, if the doctrine of equivalents does not apply to functional expression claims, then no positive precedents would arise in that direction either, so such a negative rationale is unavoidable.

Furthermore, in each of the above precedents, even if a functional expression claim had been drafted at the time of filing using a higher-level concept encompassing the common functions, it would not have affected patentability, and infringement would have been easier to establish.In other words, it is precisely because the claims are in such a situation that the doctrine of equivalents is applied to provide relief and achieve equity. In this way, the application of the doctrine of equivalents is considered to be a theory for expanding the scope of rights from an equity perspective in cases where, despite the possibility of creating claims using a higher-level functional expression (such as “lifting and lowering drive means” or “hooking means” in the above example), the claims were instead described at a more specific level.

As in the U.S. test for hypothetical claims, if the claim had been drafted using functional expressions of higher-level concepts, and if the claim would have been unpatentable in the first place, the doctrine of equivalents should not be applied. Therefore, the fact that the doctrine of equivalents may be applied implies that the claim could have been drafted using functional expressions in the first place.

From this, it can be said that if claims using functional expressions are properly drafted (capturing the appropriate functions), the issue of applying the doctrine of equivalents does not arise. Therefore, in infringement cases, the fact that infringement is recognized only after the doctrine of equivalents is applied is, at least in Japan, often not very honorable for the drafters of the specification.However, if the inventor was unaware of the appropriate “function” as the higher-level concept at the time of filing, or if such awareness was not possible given the technical level at the time of filing, this may be unavoidable. Even in such cases, as demonstrated by the Supreme Court in this case, if the determination of equivalence is based on the time of infringement, the doctrine of equivalents may be recognized regardless of the inventor’s subjective circumstances, provided that the “person skilled in the art” could have substituted the claimed feature at the time of infringement.

(5) Other matters to be considered

1. Relationship between the breadth of functions
Even if it is considered that the doctrine of equivalents does not apply to functional expression claims, it is necessary to consider classifying functional expression claims. That is, the relationship between the structural elements indicated by “function + means” and the more specific structural elements contained therein is a relationship between a higher-level concept and a lower-level concept.

subordinate concepts. If the doctrine of equivalents is applied to expand the scope of rights from the subordinate concept to the superior concept under this relationship (identity of functions), then even in the case of functional expressions, if there are elements in a superior-subordinate relationship, it may be possible to consider the application of the doctrine of equivalents to narrowly defined functional expressions, similar to the consideration of broader functional equivalents.

2. Specific Considerations
A specific example of this is when the scope of the patent claims is unnecessarily narrow, such as when the function of a component in the invention as a whole is not accurately captured, resulting in unnecessary functional limitations.

For example, if the claim uses the functional expression “lifting means” because a means for moving an object up and down is necessary, but the function that the structural element should perform is not limited to up and down movement and could include horizontal movement to move the position of the object, then the functional expression “lifting means” may be too narrow. In this case, the means for moving horizontally used in Object No. 1 does not use “lifting means.”However, the functions actually performed in the invention are the same, and from the perspective of the higher-level function of moving the position, it could be considered within the scope of interchangeability. In other words, despite the need to accurately capture the technical role of the means and describe a broader range (higher-level concept) of functions, the functions were overly limited.As a result, an object of the prior art may arise that possesses the common higher-level function (minimum necessary function) and has structural elements with functions different from those described in the claims.

In such a case, should the equivalent theory be applied to deem Item I an infringing product? This situation is similar to cases where the equivalent theory is applied to claims that describe specific structural elements rather than functional expressions, such as when unnecessary numerical limitations are imposed on functional expressions. Simply because functional expressions are used does not mean that equivalence should be denied from the outset, as this would not be equitable. Therefore, it can be argued that the equivalent theory should be applied.

However, in this paper, we have argued that the doctrine of equivalents should not be applied to functional expression claims. Therefore, even in the above case, where there is a broad-narrow relationship between functions and the claim has been drafted in a way that inaccurately narrows the functions of the components, we do not wish to recognize an exception to the doctrine of equivalents. Instead, we argue that the doctrine of equivalents should not be applied even in such cases.In other words, in Japan, where there is a high degree of freedom in functional expressions, when using functional expressions that inherently possess a broad scope as a technical concept, one should recognize that the scope of rights is limited to the range of the function itself. This is the risk associated with using functional expression claims, and we believe it aligns with the principles of fairness and legal stability.

3. Additionally, regarding functional limitations of the elements of the claims, when the function of the corresponding element of the prior art falls under the functional combination type that includes the claimed function, the matter was discussed in Section 7(3) above.

8. Summary

The application of the doctrine of equivalents to patent claims that accurately express functions is inherently contradictory. From the perspective of rights protection, it is sufficient to determine whether the function in question falls within the scope of the inherently broad “function” and to recognize infringement within that scope.

Additionally, in the United States, as far as I am aware, there is no clear ruling that the ordinary doctrine of equivalents applies to a configuration expressed in means-plus-function terms after the application of USP 112(6). This is naturally the case given the purpose of USP 112(6) to limit the scope of rights.Conversely, there are rulings that hold that if a claim is examined under Section 112(6) of the USP and determined not to be an equivalent under the means-plus-function doctrine, it also does not constitute an infringement under the ordinary doctrine of equivalents (Odetics Inc. v. Storage Technology Corp., E.D. Va., No. 95-881-A, July 31, 1998).

Finally, considering the freedom of claim drafting for functional expression claims in Japan, it is natural to conclude that Japan is stricter (more conservative) in applying the doctrine of equivalents to claims that do not use functional expressions.In other words, when determining the scope of rights based on claims created by imposing specific structural limitations due to differences in the regulatory environment regarding the use of functional expressions, there is no need for the doctrine of equivalents to apply the same standards as in the United States. Conversely, even if the standards are nearly identical, the strictness of the doctrine of equivalents would naturally differ.