The scope of a patent right is determined by the claim(s)[1]. The appropriateness of the recitation in the claim(s) is imperative to both the patentee’s scope of protection when the patent issues and the restriction on the public use. Each claim should be recited with clarity and conciseness, and be supported by the specification[2]. Also, the manners of disclosure for claim(s) are prescribed in the Enforcement Rules of the Patent Act as well as the Patent Examination Guidelines. According to Paragraph 2 of Rule 18 of the Enforcement Rules of the Patent Act: “an independent claim shall state the designation of the subject matter as claimed and the essential technical features of the invention that the applicant regards as his/her invention,” it seems to left to the “applicant” to decide whether the claim comprises the essential technical features. In other words, under this regulation, any technical features recited in the claim can be considered as essential technical features of the invention as regarded by the applicant. However, if it is left to the “applicant” to determine whether the claim contains the essential technical features, since the more technical features introduced will make the scope of the patent right narrower, there is no incentive for the applicant to make an objective determination as to whether the claim contains the essential technical features, which makes this regulation useless. In comparison, according to the Patent Examination Guidelines[3]: “essential technical features refer to the technical features that are indispensable for solving the problem of the claimed invention, which as a whole constitute the technical means of the invention, and is the basis of comparison between the claimed invention and the prior art,” when determining whether the essential technical features are included in an independent claim, it should be based on the purpose of the invention described in the specification and then determine whether the technical features recited in the claim are sufficient to attain the purpose or effect stated in the specification. In this regard, it appears that “the essential technical features of the invention that the applicant regards as his/her invention” is not a necessary condition. Therefore, this article takes the 2022 Xing Zhuan Su Zi No. 61 judgment rendered by the Intellectual Property and Commercial Court (IPCC) on August 17, 2023 as an example to analyze the current standards for courts in determining whether a claim contains essential technical features, and use this analysis as a basis for applicants/patentees to draft patent claims or rebuttals, as well as suggestions for future amendments to the Enforcement Rules of the Patent Act.
 
The invention patent in dispute underwent an invalidation action. The patentee (i.e., the intervener) filed a post-grant amendment for amending the independent claims 1, 20 and 28 and deleting the dependent claim 12 on May 14, 2021. The Taiwan Intellectual Property Office (TIPO), namely the defendant, held a hearing on July 22, 2022 and conducted an examination on the patent at issue based on the post-grant amendment. After examination, the TIPO issued a decision that “the post-grant amendment filed on May 14, 2021 should be approvable,” “the invalidation action against claims 1-11 and 13-29 is considered groundless” and “the invalidation action against claim 12 is dismissed.” Since the decision was rendered based upon the hearing, no administrative appeal is required for the purpose of institution of an administrative remedial proceeding according to Article 109 of the Administrative Procedure Act. Hence, the invalidation requester (i.e., the plaintiff) directly filed this administrative litigation with the IPCC.
 
During litigation, the plaintiff argued that[4]: “based on the technical features disclosed in figures 5a and 5b of the evidence item 13, namely the wavelength shift is indeed subject to variations in the thickness of each layer of the film. Therefore, claims 1, 20 and 28 are required to disclose a specific thickness of each layer of the film, or a specific layer thickness relationship to be satisfied in order to achieve a wavelength shift of less than 20 nm. However, claims 1, 20 and 28 do not define the thickness of each layer of the filter structure. As a result, it is impossible to determine that the shift of the center wavelength of the passband of the optical filter described in the claims must be less than 20 nm. Consequently, the claims lack the technical features that are indispensable for the problem that the claimed inventions aim to solve, and do not conform to the provisions of Paragraph 4 of Article 26 of the Patent Act and Paragraph 2 of Rule 18 of the Enforcement Rules of the Patent Act.” The IPCC, however, did not accept the plaintiff’s arguments.
 
In the judgement, the IPCC held that [5]: “according to the descriptions recited in line 14 on page 2, line 8 on page 3 and line 24 on page 10 to line 1 on page 11 of the specification of the patent at issue, it can be understood that the purpose of the patent at issue is to ‘improve the signal-to-noise ratio of the systems of the conventional optical filters.’ Therefore, based on the technical features ‘improving the hydrogenated silicon material to have a suitably low extinction coefficient (i.e., an extinction coefficient of less than 0.0005) over the wavelength range of 800 nm to 1100 nm’ and ‘with a change in angle of incidence, the shift of the center wavelength reaches an upper limit,’ the purpose of the patent at issue ‘improving the signal-to-noise ratio of the systems of the conventional optical filters’ can be attained. Accordingly, the technical features ‘fewer layers’ and ‘smaller total coating thickness’ should be used to reduce the ‘expense and coating time involved in fabricating the conventional optical filters,’ but not for the purpose of the patent at issue ‘improving the signal-to-noise ratio of the systems of the conventional optical filters.’ Since all of claims 1, 20 and 28 have recited that ‘the hydrogenated silicon layers have an extinction coefficient of less than 0.0005 over the wavelength range of 800 nm to 1100 nm’ and ‘wherein the passband has a center wavelength that shifts by less than 20 nm in magnitude with a change in an incidence angle between 0° to 30°,’ a person having ordinary skill in the technical field pertinent to the patent at issue can clearly understand the significance of the contents described in claim 1, 20 and 28 and achieve the purpose of the patent at issue ‘improving the signal-to-noise ratio of the systems of the conventional optical filters.’ Therefore, claims 1, 20 and 28 have stated the essential technical features of the claimed inventions. On the contrary, by referring to line 18 on page 2 of the specification of the patent at issue, which describes that ‘the large number of layers in the filter stacks and blocking stacks increases the expense and coating time involved in fabricating these conventional optical filters. The large total coating thickness also makes these conventional optical filters difficult to pattern, e.g., by photolithography,’ it should be understood that the technical features ‘fewer layers’ and ‘smaller total coating thickness’ disclosed in the specification of the patent at issue are intended to reduce the expense and coating time involved in fabricating the conventional optical filters. Therefore, the film thickness, the number of film layers and the film thickness relationship between each film layer in the patent at issue are not the technical features that are indispensable for the problem that the claimed inventions aim to solve.” Based on the foregoing reasons, the IPCC concluded that claims 1, 20 and 28 have already stated the essential technical features of the claimed inventions and the patent at issue thus conforms to the requirements of Paragraph 4 of Article 26 of the Patent Act and Paragraph 2 of Rule 18 of the Enforcement Rules of the Patent Act.
 
From the above judgment, it can be seen that the IPCC, in determining whether a claim contains essential technical feature(s), does not leave it to the applicant (patentee) to determine whether the claim comprises the essential technical feature(s), but rather, based on the purpose of the invention described in the specification, determines whether the technical feature(s) stated in the claim is sufficient to achieve the purpose of the invention or the effect of the technical solution for solving the problem. Also, in practice, there are cases[6] where the IPCC disagreed with the patentee’s argument and considered that the claim(s) did not contain the essential technical feature(s). Therefore, based on the analysis of the relevant judgments rendered by the IPCC in recent years, the author suggests that when drafting patent claims, the applicant should clearly describe the purpose of the invention and the effect to be achieved in the specification, and make sure that the claims contain technical features that are closely related to the purpose of the invention. Moreover, in order to achieve the purpose of the Patent Act, avoid or mitigate disputes, and further enhance the patent examination quality, it is suggested that when the Enforcement Rules of the Patent Act is revised in the future, the content of Paragraph 2 of Rule 18 may be amended to read “an independent claim shall state the designation of the subject matter as claimed and the technical features as being essential for carrying out the invention.”