7.5.1 Claim construction
The principles of claim construction derive from the purpose of the patent system.183 The Supreme Court has stated that
[t]he purpose of the patent system shall be to encourage inventions and thereby to contribute to the development of the industry by granting exclusive rights (patents) to applicants who disclose their inventions. On the one hand, the patent system can protect inventions which patentees have developed. On the other hand, it facilitates the utilization of inventions by third parties through their disclosure (Patent Act, Article 1).184
In this way, the patent system grants an exclusive right in exchange for the applicant’s disclosure of a patent to the public.185
In patent infringement lawsuits, it is important to determine the scope of this exclusive right while balancing the protection of the patented invention and the interest of third parties to freely operate outside the scope of the patented invention.
7.5.1.1 Claim wording
Taking the purpose of the patent system into consideration, Article 70(1) of the Patent Act provides that “[t]he technical scope of a patented invention shall be determined on the basis of the statements of the patent claims attached to the application.” There is a similar principle in both U.S. and European patent law.186
According to this principle, all the elements and limitations stated in the claims must be present in the defendant’s product to establish infringement. It is only when this principle is satisfied that a defendant’s product will fall within the technical scope of a patented invention. Therefore, these claims have a special status compared to other sources for interpretation. It is not possible to use elements that are not mentioned in the claims – such as from the specification and other sources – to interpret a claim more narrowly than was originally intended.187 In other words, patent law provides that claims are to be interpreted according to the wording of the claims and that the wording is both the starting point and the goal.
Article 36(5) of the Patent Act provides that the applicant must state in the claims all the matters necessary for specifying the invention for which a patent right is sought. Such claims have the function of providing a third party with the most important tools to understand the content of the patented invention.
7.5.1.2 Interpreting the claims
When interpreting the wording of the claims, the standard applied is usually the natural meaning from the point of view of a person having ordinary skill in the art. The technical scope of the patented invention must be established based on the claim terms without any broadening or narrowing of their meaning.
Article 24 of the Patent Law Enforcement Regulation provides that the technical terms in the specification should be academic terms that are used in their usual sense and uniformly throughout the specification. Furthermore, the terms must be defined if they are used to indicate a specific meaning.188 However, claim terms are abstract when compared to, for example, the certainty provided by a boundary line in real property. They are not defined as a particular tangible object and can be esoteric. Therefore, other materials are usually required for claim construction.
7.5.1.3 Sources for claim construction
According to Article 70(2) of the Patent Act, “the meaning of the claim terms shall be interpreted in light of specifications and the drawings.” Therefore, the detailed description of the invention in the specification and the drawings is prescribed by statute as a source for interpreting patent claims.
The prosecution file history of the patent, publicly known art, as well as common knowledge of the art can also be relevant sources for claim interpretation. Even though those sources are not provided for in statute, they are legitimate sources similar to specifications and drawings.189
The key rationale for allowing non-statutory sources such as publicly known art to be used to interpret claims is disclosure to third parties: specifications and drawings are disclosed to a third party in the one document with the claims. Additionally, according to Article 186 of the Patent Act, the prosecution file history can be viewed by any third party. Further, publicly known art and common knowledge of the art is technical information that is naturally possessed by a person having ordinary skill in the art.
7.5.1.4 How to use sources
One issue in patent litigation is how all this information should be taken into consideration to properly construe the claim terms. As is the case for specifications and drawings, it is not possible to introduce elements that are not mentioned in the claims and thus to interpret the claim terms more narrowly than originally intended. However, in patent infringement lawsuits, the file history, publicly known art or common knowledge of the art can sometimes be a deciding factor when the claim construction is disputed. Establishing publicly known art and common knowledge in the art are also very important. These matters are supposed to be already possessed by persons having ordinary skill in the art, who are readers of the claims and specifications.
7.5.1.5 Product-by-process claims
Product-by-process claims can be defined as claims for inventions of products that recite the manufacturing processes of the products. The Supreme Court has stated, in a case involving this type of claim, that “[e]ven in such a case, the technical scope of the patented invention is determined as a product having the same structures and properties, which is manufactured by the described processes.”190 In the same case, the Supreme Court ruled that the patents were invalid because they were contrary to the principle of claim clarity under Article 36(6)(ii) of the Patent Act and stated that such claims will conform to the principle of claim clarity only when there are circumstances where it is impossible or almost impractical to request the applicant to directly identify the product by its structure or properties. For instance, when it is technically impossible for the applicant to directly identify the object by its structure or properties, or it takes excessive economic expenditure or time to perform the identification work.191
Conversely, if these requirements are met, the specifications will disclose the invention of a product and not a process. In that case, it is an insufficient defense to argue that the product has been manufactured by a different process. However, in the absence of impossible or impractical circumstances, as outlined by Supreme Court above, a product-by-process claim is invalid because it runs counter to the principle of claim clarity.
Therefore, with regard to the claim wording of a manufacturing process, it cannot be assumed that all claims that contain any steps as part of a process fall within product-by-process claims. This is to be determined from a substantive and practical point of view in order not to invalidate patented inventions that have not yet been identified as product-by-process claims. In this context, it has been pointed out that, in practice, it is important to appropriately limit the scope of the application of the Supreme Court decision.192
When the claims are determined not to be a product-by-process claim – even though they contain a manufacturing process – those processes must constitute elements or limitations in the claims so that, in accordance with the basic principle of claim interpretation, a product manufactured with a different process is not covered by the technical scope of the patented invention.
7.5.1.6 Functional claims
Functional claims are defined as claims that “are described by not concrete structures but absolute functions of the structures.”193 An example would be when the function of glue, rather than its chemical structure, is described in the claims, using words such as “adhesive means.” As stated above, Article 36(5) of the Patent Act provides that an applicant must state in the claims all the matters necessary for specifying the invention for which a patent right is sought. Functional claims comply with this requirement and are well established in practice.
The technical scope of functional claims must be determined based on the technical idea embodied in the specific structures disclosed in the specification. This does not mean that the scope of the claims is limited to the embodiments. A structure that is not described in the embodiments but that a person having ordinary skill in the art can determine from the structure disclosed in the specification or from the detailed description of the invention is to be included in the technical scope of the invention.
It can be difficult to understand to what extent identifying particular features of embodiments is allowed. Establishing publicly known art and common knowledge in the art can help deal with this issue. These are matters that are supposed to be possessed by persons having ordinary skill in the art, who are readers of the claims and the specifications, and whose understanding is deemed to show the technical scope of the patented invention.