Open Decision Ledger · IP, data & telecommunications
Patent infringement, equivalents, and the core of the technical idea
Supreme Court, Mar. 11, 2021, 2019Da237302 (judgment)
No holding summary · checked against points at issue. The official text publishes no summary of the holding for this decision. The quotation and factors in this record are copied verbatim from the points at issue; the evidence for each axis is taken from the points at issue, the order and the reasons.
Case name: 특허권침해금지등청구의소
Official text on the National Law Information Center
Question
Where a part of the construction recited in the claim has been modified, what requirements must the accused product meet before it is held equivalent, how is it decided whether its problem-solving principle is the same as the invention's, and where the core of the technical idea was already public at the filing date, by what is substantial identity of action and effect judged?
Holding
Where a part of the claimed construction is modified, the accused product is equivalent, absent special circumstances, if it shares the same problem-solving principle, produces substantially the same action and effect, and the modification is one that any person with ordinary knowledge in the field could easily think of. That sameness is judged by ascertaining, with the description and the prior art at the filing date in mind, the core of the technical idea on which the solution means peculiar to the invention rests. Where that core was already public at the filing date or is nothing different from it, substantial identity of action and effect must instead be judged by comparing the individual functions and roles of the corresponding elements.
Points at issue, verbatim
발명의 설명 기재와 출원 당시 공지기술 등을 참작하여 파악되는 특허발명에 특유한 해결수단이 기초하고 있는 기술사상의 핵심이 침해제품 등에서도 구현되어 있는 경우, 작용효과가 실질적으로 동일하다고 보아야 하는지 여부(원칙적 적극) 및 기술사상의 핵심이 특허발명의 출원 당시에 이미 공지되었거나 그와 다름없는 것에 불과한 경우, 작용효과가 실질적으로 동일한지 판단하는 방법
Unofficial English translation
Where the core of the technical idea on which the solving means peculiar to the patented invention, as grasped in consideration of the description of the invention and the prior art, etc. at the time of filing, is based is also embodied in the infringing product or the like, whether the operation and effect must be regarded as substantially the same (affirmative in principle) and, where the core of the technical idea was already publicly known at the time of filing of the patented invention or is nothing more than something equivalent thereto, the method of determining whether the operation and effect are substantially the same
Disposition
Partly reversed and remanded Stated in the decision
원심판결 중 피고 패소 부분을 파기하고, 이 부분 사건을 특허법원에 환송한다.
Unofficial English translation
The judgment of the court below is reversed insofar as it goes against the defendant, and this part of the case is remanded to the Patent Court.
Form of the test
Elements stated Stated in the decision
특허발명과 과제 해결원리가 동일하고, 특허발명에서와 실질적으로 동일한 작용효과를 나타내며, 그와 같이 변경하는 것이 그 발명이 속하는 기술분야에서 통상의 지식을 가진 사람 누구나 쉽게 생각해 낼 수 있는 정도라면
Unofficial English translation
where the patented invention and the accused product share the same principle of solving the problem, exhibit substantially the same operation and effect as in the patented invention, and such modification is of such a degree that anyone having ordinary knowledge in the technical field to which the invention pertains could readily conceive of it
Factors
- 침해제품 등이 특허발명의 청구범위에 기재된 구성과 균등한 것으로서 특허권을 침해한다고 보기 위한 요건
- 침해제품 등과 특허발명의 과제 해결원리가 동일한지를 판단하는 방법
- 발명의 설명 기재와 출원 당시 공지기술 등을 참작하여 파악되는 특허발명에 특유한 해결수단이 기초하고 있는 기술사상의 핵심이 침해제품 등에서도 구현되어 있는 경우
- 기술사상의 핵심이 특허발명의 출원 당시에 이미 공지되었거나 그와 다름없는 것에 불과한 경우
- 작용효과가 실질적으로 동일한지 판단하는 방법
Unofficial English translation
• The requirements for regarding an infringing product or the like as being equivalent to the components set forth in the claims of the patented invention and thus as infringing the patent right
• The method of determining whether the principle of solving the problem of the infringing product or the like and that of the patented invention are the same
• Where the core of the technical idea on which the solving means peculiar to the patented invention, as grasped in consideration of the description of the invention and the prior art, etc. at the time of filing, is based is also embodied in the infringing product or the like
• Where the core of the technical idea was already publicly known at the time of filing of the patented invention or is nothing more than something equivalent thereto
• The method of determining whether the operation and effect are substantially the same
Relation to precedent
Follows earlier decisions Stated in the decision
대법원 2019. 1. 31. 선고 2017후424 판결(공2019상, 702), 대법원 2020. 4. 29. 선고 2016후2546 판결
Unofficial English translation
Supreme Court Decision 2017Hu424 decided January 31, 2019 (Gong 2019 Sang, 702), Supreme Court Decision 2016Hu2546 decided April 29, 2020
Decisions referred to
[1] 대법원 2019. 1. 31. 선고 2017후424 판결(공2019상, 702), 대법원 2020. 4. 29. 선고 2016후2546 판결 / [2] 대법원 2019. 1. 31. 선고 2018다267252 판결(공2019상, 633), 대법원 2019. 2. 14. 선고 2015후2327 판결
Burden of proof
Not addressed Not in the decision
Open question and revisit condition
Where a prior application discloses an integrally formed elastic catching member, how substantial must the rearrangement be before changing a pin member supported by a separate spring into a catching member exceeds what an ordinarily skilled person could easily think of?
The remand judgment of the Patent Court, specifying the claim amount for each product and recalculating damages, will show how the comparison of individual functions is applied. A later Supreme Court decision changing the doctrine of equivalents, or an amendment to Articles 97, 126 and 128 of the Patent Act, would require this entry to be read again.
Cross-family AI independent reading & axis check
7 of 8 axes matched GPT-6 Astra (OpenAI, codex CLI) · 2026-10-25
A reader from another model family (GPT-6 Astra), given the official text but not the primary reading, agreed on 7 of the 8 axes; the readings differed on axis 8 (open question and revisit condition).
Axis 8 (Open question and revisit condition): Primary “Where a prior application discloses an integrally formed elastic catching member, how substantial must the rearrangement be before changing a pin member supported by a separate spring into a catching member exceeds what an ordinarily skilled person could easily think of?” vs Independent “What damages are attributable to the first accused product once the claims for each product are separately specified on remand?”
The primary reading asks how substantial a rearrangement must be to go beyond what a skilled person could easily conceive, given a prior-art integral elastic catching member. The independent reading asks what damages are attributable to the first product on remand.
발명의 설명 기재와 출원 당시 공지기술 등을 참작하여 파악되는 특허발명에 특유한 해결수단이 기초하고 있는 기술사상의 핵심이 침해제품 등에서도 구현되어 있는 경우, 작용효과가 실질적으로 동일하다고 보아야 하는지 여부(원칙적 적극) 및 기술사상의 핵심이 특허발명의 출원 당시에 이미 공지되었거나 그와 다름없는 것에 불과한 경우, 작용효과가 실질적으로 동일한지 판단하는 방법Raw responses and comparison record: Protocol · Blind readings (JSONL) · Axis comparison (JSONL) · SHA-256 (JSON)
Lower-court contrast & scope of application
Lower-court reading vs. Supreme Court holding
Lower-court context: The Patent Court, in its judgment of 9 May 2019 (2018Na1701), held that the 'pin member and second elastic spring' of claim 1 and the 'button and catching member' of Defendant 2's accused product rest on the same problem-solving principle, produce substantially the same action and effect, and were easy to conceive, and so found infringement. It granted the injunction and destruction sought against Defendant 2's product and, without distinguishing between the two accused products, calculated total damages under Article 128(4) of the Patent Act at KRW 135,965,212, of which it added KRW 115,965,212 and interest beyond the KRW 20,000,000 the first instance had awarded, dismissing the plaintiff's remaining appeal.
Supreme Court standard: The Supreme Court found the technical ideas drawn from the description already disclosed in published Japanese patent and utility model gazettes at the filing date, so they were not peculiar to the invention and could not serve as the basis for judging substantial identity. Comparing the corresponding elements, it held that Defendant 2's product detaches the handle only after rotating the lever and then pressing the button, that its catching member is elastically formed as one piece, and that changing the pin member into a catching member would require a substantial rearrangement with no hint or motive in the invention. Because the appellate judgment left it impossible to tell how much damages it had found for Defendant 2's product, so that the part the defendants attacked was not identified, the Court reversed the whole of the portion in which the defendants lost and remanded to the Patent Court.
Distinguishing conditions
- An accused product containing every element recited in the claim and the organic combination between those elements unchanged, so that no modification arises.
- A case in which the core of the technical idea was not public at the filing date and is peculiar to the invention, so that it may still be the yardstick for substantial identity.
- An accused product containing an element equivalent to the pin member and the second elastic spring, so that the corresponding elements are not different as here.
Record verification notes
Check first whether the core of the technical idea was public at the filing date, since that decides which route to take. Then set each difference, here differences 1 and 2, against the corresponding elements, and gather what shows or negates a hint and motive for the change. Specify the claim amount for each defendant's product separately, so that the scope of any appeal is identifiable.
From the official text
Points at issue
[1] 특허권침해소송의 상대방이 제조하는 제품 또는 사용하는 방법 등이 특허권을 침해하는지 판단하는 기준 / 침해제품 등에 특허발명의 청구범위에 기재된 구성 중 변경된 부분이 있는 경우, 침해제품 등이 특허발명의 청구범위에 기재된 구성과 균등한 것으로서 특허권을 침해한다고 보기 위한 요건 및 여기서 침해제품 등과 특허발명의 과제 해결원리가 동일한지를 판단하는 방법 [2] 발명의 설명 기재와 출원 당시 공지기술 등을 참작하여 파악되는 특허발명에 특유한 해결수단이 기초하고 있는 기술사상의 핵심이 침해제품 등에서도 구현되어 있는 경우, 작용효과가 실질적으로 동일하다고 보아야 하는지 여부(원칙적 적극) 및 기술사상의 핵심이 특허발명의 출원 당시에 이미 공지되었거나 그와 다름없는 것에 불과한 경우, 작용효과가 실질적으로 동일한지 판단하는 방법
Unofficial English translation
[1] Criteria for determining whether the products manufactured or the methods used, etc. by the opposing party to a patent infringement suit infringe the patent right / Where an infringing product or the like has a modified portion among the components set forth in the claims of the patented invention, the requirements for regarding the infringing product or the like as being equivalent to the components set forth in the claims of the patented invention and thus as infringing the patent right, and the method of determining whether the principle of solving the problem of the infringing product or the like and that of the patented invention are the same [2] Where the core of the technical idea on which the solving means peculiar to the patented invention, as grasped in consideration of the description of the invention and the prior art, etc. at the time of filing, is based is also embodied in the infringing product or the like, whether the operation and effect must be regarded as substantially the same (affirmative in principle) and, where the core of the technical idea was already publicly known at the time of filing of the patented invention or is nothing more than something equivalent thereto, the method of determining whether the operation and effect are substantially the same
Summary of the holding
The official text publishes no summary of the holding for this decision. The quotation and factors in this record are copied verbatim from the points at issue; the evidence for each axis is taken from the points at issue, the order and the reasons.
Order
원심판결 중 피고 패소 부분을 파기하고, 이 부분 사건을 특허법원에 환송한다.
Unofficial English translation
The judgment of the court below is reversed insofar as it goes against the defendant, and this part of the case is remanded to the Patent Court.
Provisions referred to
[1] 특허법 제97조, 제126조, 제128조 [2] 특허법 제97조, 제126조, 제128조
Read 2026-10-25 · Cross-read 2026-10-25. All quotes matched against the official text. The Chinese-character placeholders the court used for anonymised parties are given in their Korean readings, and parenthetical Chinese-character glosses are omitted.
Every entry is published only after all quotes have been matched character by character against the official text, and audited by an independent second reading from a different model family across all eight axes. Both agreed axes and text-grounded interpretive divergences are recorded openly. The ledger is a research record, not an assessment of the court or advice on any matter.
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