How are selection inventions treated in Korea?

Chanjoong Kim, Partner · Published 13 November 2026

Last verified 9 October 2026

At a glance

“Selection invention” is a term of case law and the Examination Guidelines

The Patent Act has no provision specific to selection inventions. Novelty and inventive step of a selection invention are assessed under Patent Act, Art. 29(1) and Art. 29(2). [1][9]

The Supreme Court of Korea defined a selection invention in Supreme Court Decision 2001Hu2740 Decided April 25, 2003. The starting point is a prior or publicly known invention in which a constituent element is stated as a generic concept. A selection invention is an invention in which all or part of the constituent elements consist only of a specific concept included in that generic concept. [3]

The Examination Guidelines use the term in the same sense. The basis is Part III, Chapter 3, 6.4.1 of the Examination Guidelines. A selection invention is an invention that selects, as part of its essential elements, matter that is not directly disclosed in the cited invention. [2]

The standard for selection inventions is used both in examination and after registration. A violation of Art. 29 is a ground for rejection under Patent Act, Art. 62, subparagraph 1, and a ground for invalidation under Art. 133(1), subparagraph 1. [1] A violation of Art. 29 is also a ground for a request for revocation of a granted patent under Art. 132-2(1), subparagraph 1. However, a case based on an invention under Art. 29(1), subparagraph 1 is excluded from that ground. [1] Art. 132-2(2) provides that a request for revocation of a granted patent cannot be filed on a ground based on prior art published in the Patent Gazette under Art. 87(3), subparagraph 7. Art. 87(3), subparagraph 7 is the provision under which, where a notified ground for rejection contains information on prior art, that information is included in the publication of registration. [1]

The Supreme Court decisions cited in this article come from three kinds of proceedings. Decisions 2001Hu2740 and 2012Hu3664 are cases in which the application was rejected. [3][8] Decisions 2008Hu736, 743 and 2019Hu10609 are invalidation cases. [4][9] Decision 2021Hu10022 concerns a decision to revoke the patent, issued on a request for revocation of a granted patent. [14]

A general formula of chemical compounds is the typical example. The prior art document states a chemical formula in Markush format, and the later application claims a particular compound within that scope. [9] The issue also arises for medical uses (medicinal uses). In Supreme Court Decision 2012Hu3664 Decided May 16, 2014, the prior art disclosed a use of a class of drugs, which was the generic concept. The Supreme Court treated the part of the claim directed to the same use of one drug in that class as a selection invention. [8]

Novelty is denied only when the prior art document specifically discloses the specific concept

The fact that the prior art states a generic concept is not enough to deny the novelty of a selection invention. The leading decision is Supreme Court Decision 2008Hu736, 743 Decided October 15, 2009. To deny novelty, the prior art must specifically disclose the specific concept that makes up the selection invention. [4]

Specific disclosure covers two cases. One is the case where the prior art document contains a literal statement of the selection invention. The other is the case where a person skilled in the art can directly recognize the existence of the selection invention from the prior art document. That recognition is based on the content of the prior art document and the common general technical knowledge at the time of filing. [4]

An optical isomer case shows how this standard is applied. The prior art document in Decision 2008Hu736, 743 stated that the compound exists as two optical isomers. It also stated that the invention related to each of the isomers and to their mixture. The Supreme Court found that the claim directed to the dextrorotatory optical isomer lacked novelty. [4] The Supreme Court also stated that the separation method or the possibility of separation does not have to be disclosed in the prior art document. [4] Supreme Court Decision 2008Hu3469, 3476 Decided March 25, 2010 applied the same standard. [6]

The novelty part of the Examination Guidelines points in the same direction. Part III, Chapter 2, 4.4(1) of the Examination Guidelines states that a claim normally has novelty when the claim is a specific concept and the cited invention is a generic concept. However, novelty can be denied when the invention of the specific concept can be derived as self-evident from the cited invention. The common general technical knowledge at the time of filing is taken into account in this assessment. [2] The Examination Guidelines also state that the mere fact that a specific concept is included in a generic concept does not mean that it can be derived as self-evident. [2]

The difficulty of the technical configuration cannot be skipped in the inventive step analysis

Supreme Court Decision 2019Hu10609 Decided April 8, 2021 held that the general standard for inventive step also applies to selection inventions. Even when a generic concept of the patented invention is publicly known from the prior art, inventive step is not denied if the difficulty of the technical configuration is recognized. [9]

Decisions before Decision 2019Hu10609 stated the standard in terms of the effect. Decision 2008Hu736, 743 stated the requirement for the inventive step of a selection invention not to be denied. All of the specific concepts must have an effect that is qualitatively different from the prior art, or a quantitatively remarkable difference. [4] Decision 2019Hu10609 explained the meaning of this statement. It means that, in a case where the difficulty of the technical configuration is hard to recognize, inventive step is not denied if the effect is remarkable. [9] The difficulty of the technical configuration therefore cannot be skipped merely because the generic concept is publicly known. Inventive step must not be decided only on whether the effect is remarkable. [9]

Decision 2019Hu10609 stated that the difficulty of the technical configuration is assessed by considering factors such as the following together. [9]

• The number of compounds that can theoretically be included within the chemical formula and the range of substituents of the prior art
• Whether there is a circumstance, motivation or suggestion that would lead a person skilled in the art to select a particular compound or a particular substituent among them preferentially or easily
• The structural similarity between the compounds specifically stated in the prior art and the patented invention

The effect is also used in assessing the difficulty of the technical configuration. Decision 2019Hu10609 stated that, if the effect of the invention is remarkable compared with the prior art, this is strong material for inferring the difficulty of the technical configuration. [9] Even when the assessment of the difficulty of the technical configuration is unclear, inventive step is not denied if there is an effect that is different in kind or quantitatively remarkable. [9]

In case 2019Hu10609, the Supreme Court reversed the judgment of the Intellectual Property High Court of Korea (Patent Court of Korea) and remanded the case. The chemical formula of the prior art theoretically included hundreds of millions of compounds or more. None of the 107 compounds specifically stated in the prior art had a structure similar as a whole to the patented invention. The Supreme Court stated that deriving the configuration cannot be regarded as easy unless it is judged with hindsight, knowing the content of the invention. [9]

There is also a case in which inventive step was denied under the same standard. Supreme Court Decision 2020Hu11738 Decided February 2, 2023 is an example. The patented invention differed from a compound of an embodiment of the prior art in only one terminal substituent. The difference was between a methoxy group and an ethoxy group. The lower court found that this substitution was one that would be tried preferentially. The Supreme Court stated that the lower court’s reasoning was inappropriate in part, because it concluded that the configuration was not difficult without considering the effect. [10] However, the Supreme Court stated that obtaining a somewhat improved effect through such a substitution is not enough to regard the effect as remarkable. It found the conclusion of the lower court to be correct. [10]

The legal principle of Decision 2019Hu10609 has also been applied to a compound case outside pharmaceuticals. Supreme Court Decision 2021Hu10022 Decided May 30, 2024 concerns compounds for organic electroluminescent devices. A compound specifically disclosed in the prior art had the same structure as some of the compounds of the patented invention and differed only in the position of substitution. There was also no negative teaching or suggestion against substitution at that position. The Supreme Court found that the configuration could not be regarded as difficult and that no remarkable effect could be recognized, and it denied inventive step. [14]

The Examination Guidelines also reflect Decision 2019Hu10609. Examination Guidelines 6.4.1 states that inventive step must not be decided only on whether the effect is remarkable, without examining the difficulty of the technical configuration. [2] The earlier principle also remains in the same section. Selecting what is optimal or suitable from publicly known art by experiment is generally not recognized as involving an inventive step. [2]

To rely on the effect, all of the specific concepts must have the effect

Examination Guidelines 6.4.1 states that inventive step can be recognized when a selection invention has an advantageous effect over the cited invention. In that case, all of the specific concepts included in the selection invention must have that effect. All of them must have a qualitatively different effect or a quantitatively remarkable difference. [2] This sentence comes from Supreme Court Decisions 2001Hu2740 and 2008Hu736, 743. [3][4]

Decision 2001Hu2740 is an example. The applicant submitted comparative test data showing that one optical isomer had 10 times the oral activity of the compound of the prior art. The claim also covered the racemate and the other optical isomer. The Supreme Court found it difficult to infer the effect of the other compounds from the data for one compound, and reversed the lower judgment. [3]

After Decision 2019Hu10609, the Supreme Court still examined whether all of the compounds of the claim have the effect. The claim in Decision 2021Hu10022 was directed to compounds selected from several chemical formulas. The embodiments in the specification and the additional comparative test data related to certain substituents or certain positions of substitution only. The Supreme Court stated that it was difficult to conclude that all of the compounds of the claim have a quantitatively remarkable effect. [14]

A claim that states its elements in the alternative can be rejected or revoked as a whole because of one of them. Part III, Chapter 3, 9(4) of the Examination Guidelines deals with Markush-type claims. One of the alternative elements is chosen and compared with the cited invention. If inventive step is not recognized as a result, the claim can be found to lack inventive step. [2] The same section also contains a caution not to extend the effect of one of the alternative elements to the effect of the claimed invention as a whole. The applicant can overcome the ground for rejection by deleting the alternative element that was found to lack inventive step. [2] Decision 2021Hu10022 assessed the claim in that case in the same way. It stated that, if inventive step is denied for any one of the alternative elements, inventive step is denied for the whole claim. [14]

At the application stage, a ground for rejection in one part leads to rejection of the whole application. The claim in Decision 2012Hu3664 contained a part that was a selection invention. The Supreme Court found that a quantitatively remarkable effect was not recognized for that part. That part was in an alternative relationship with the remaining part and was not organically combined with it. The Supreme Court held that the claim had to be rejected in its entirety. [8] The Supreme Court also stated that, if even one claim has a ground for rejection, the application must be rejected in its entirety. [8]

It is enough that some of several effects are remarkable. The basis is Supreme Court Decision 2010Hu3424 Decided August 23, 2012. When a selection invention has several effects, it is enough that at least some of them are recognized as different in kind or quantitatively remarkable. [7] The Supreme Court held to the same effect in Supreme Court Decision 2002Hu1935 Decided October 24, 2003, which concerned a use invention of an optical isomer. [11] In case 2010Hu3424, the comparison was made with the compounds specifically disclosed in the prior art. The Supreme Court compared the effect with the compound among them that was closest in chemical structure. It found it difficult to conclude that the therapeutic effect was remarkably superior. The Supreme Court recognized an effect of a different kind, a reduction of the side effect of increased cholesterol, and held that inventive step was not denied. [7]

The specification must state the effect clearly

The remarkableness of the effect is assessed mainly on the effect stated in the specification. In the words of Decision 2019Hu10609, it is the effect that is stated in the specification and that a person skilled in the art can recognize or infer. [9]

The comparative test data itself does not have to be included in the specification. Decision 2001Hu2740 held that it is enough to state clearly that the invention has an effect compared with the prior art. Comparative test data does not have to be stated. [3] Examination Guidelines 6.4.1 contains the same sentence. [2]

However, the level of clear statement that the Supreme Court requires is not low. Decision 2008Hu736, 743 stated what is needed for the effect to be regarded as clearly stated. There must be specific content that allows a qualitative difference to be confirmed. Otherwise, there must be a quantitative statement that allows a quantitatively remarkable difference to be confirmed. [4] Decisions 2010Hu3424 and 2012Hu3664 repeated this sentence. [7][8]

The texts of Decisions 2019Hu10609, 2020Hu11738 and 2021Hu10022 do not contain the words “quantitative statement” (정량적 기재). [9][10][14] The three decisions also did not state that they overrule earlier decisions. [9][10][14] Examination Guidelines 6.4.1 also does not contain the words “quantitative statement”, and it contains the sentence that it is enough to state clearly that there is an effect. [2]

The statement of the effect has also been an issue under the description requirements for the specification. Supreme Court Decision 2005Hu3338 Decided September 6, 2007 stated that standard. The effect as a selection invention must be stated clearly and sufficiently, to the extent that a person skilled in the art can understand it. The specification in that case stated only that the invention was “very superior” to the prior art, and the Supreme Court found that the description requirements for the specification were not met. [5] In the same decision, the Supreme Court stated that it was not appropriate for the lower court to go so far as to require that the result of the comparison be stated in quantitative figures. [5]

Decision 2005Hu3338 applied Art. 8(3) of the former Patent Act (before it was wholly amended by Act No. 4207 on 13 January 1990). That provision required a statement of the purpose, configuration, operation and effect of the invention. [5] The Reference Provisions of the decision list the current Art. 42(3) as the corresponding provision. [5] The wording of the current Patent Act, Art. 42(3), subparagraph 1 is different. It requires the description to be clear and detailed so that a person skilled in the art can easily work (practice) the invention. [1]

Experimental data submitted after filing is used only to support the effect stated in the specification. Decision 2019Hu10609 allows additional experimental data to be submitted after the filing date when the effect is in doubt. The limit is that the data must not go beyond what the specification states. [9] Examination Guidelines 6.4.1 also states that additional experimental data must not go beyond what the original specification states. [2] Decision 2021Hu10022 stated that, when the effect is in doubt, the patentee also needs to assert and prove the effect with additional experimental data. [14] In Decision 2008Hu736, 743, the Supreme Court stated that an effect that is not clearly stated in the specification cannot be considered. [4]

How Korea differs

Korea, Europe and the United States deal with the same problem in different words. The table below restates the wording of each office.

The European standard was read in the EPO Guidelines for Examination, April 2026 edition, G-VI 7 and G-VII 12. [12] The EPO Guidelines also state that the technical effect must apply to the entire range claimed. [12] The Korean Examination Guidelines and Supreme Court decisions contain the sentence that all of the specific concepts must have the effect. [2][3]

The US standard was read in MPEP 2131.02 and 2144.08. [13] MPEP 2144.08 states that the patentability of a species that falls within a prior art genus is to be analyzed no differently from any other claim. [13]

The point to check separately in Korea is the statement of the effect in the specification. The Supreme Court of Korea examined whether the effect is stated in the specification with specific content or with a quantitative statement. [4] An effect that was not clearly stated in the specification was not considered in the inventive step analysis. [4]

What applicants should do

• In general, if the claims cover a compound or composition that falls within a generic concept of a prior art document, we suggest checking the statement of the effect in the specification before filing. The check is whether the specification only says that the effect is “superior”, or whether it contains figures or specific content.
• Post-filing experimental data is used only within the scope of what the specification states. We therefore suggest stating the effect in comparison with the closest compound of the prior art already in the first application on which priority is based.
• If a claim contains several specific concepts, we suggest checking that the effect data covers all of them. For a specific concept that the data does not cover, it is worth considering a separate dependent claim or deletion.
• If a ground for rejection addresses only the effect, we suggest arguing the difficulty of the technical configuration first in the written argument. The factors of Decision 2019Hu10609 are the number of compounds covered by the prior art document, whether there is a motivation or suggestion for the selection, and the structural similarity.
• The response in an individual case depends on what the prior art document states, so please confirm it with your Korean agent.

FAQ

Does a compound that falls within a general formula of a prior art document lack novelty in Korea?

The fact that the compound falls within the general formula is not enough to deny novelty. The prior art must specifically disclose that compound. [4] Specific disclosure also covers the case where a person skilled in the art can directly recognize the existence of that compound from the prior art document. [4]

Does a selection invention lack inventive step if the effect is not remarkable?

That conclusion cannot be drawn. Under Decision 2019Hu10609, inventive step is not denied if the difficulty of the technical configuration is recognized. [9] Even when the assessment of the difficulty of the technical configuration is unclear, inventive step is not denied if there is an effect that is different in kind or quantitatively remarkable. [9]

Does comparative test data have to be included in the specification?

Decision 2001Hu2740 and Examination Guidelines 6.4.1 state that comparative test data does not have to be stated. [2][3] Decision 2008Hu736, 743 stated that there must be specific content that allows a qualitative difference to be confirmed, or a quantitative statement. [4]

Can the effect be proved with experimental data submitted after filing?

Yes. It is allowed when the effect is in doubt, to the extent that the data does not go beyond what the specification states. [9] In Decision 2008Hu736, 743, an effect that was not clearly stated in the specification was not considered. [4]

If there are several effects, do all of them have to be remarkable?

No. It is enough that at least some of the effects are recognized as different in kind or quantitatively remarkable compared with the prior art. [7]

What happens if effect data exists for only some of the compounds of the claim?

In Decision 2021Hu10022, the Supreme Court found that data for some substituents and positions of substitution was not sufficient. The reason was that it was difficult to conclude that all of the compounds of the claim have a remarkable effect. [14] In examination, the applicant can overcome the ground for rejection by deleting the alternative element that was found to lack inventive step. [2]

How DEFINE IP Law Firm handles this

DEFINE IP Law Firm checks the relationship between the generic concept of the prior art document and the claims when we review the specification before filing in Korea. If a claim may be treated as a selection invention, we check whether the statement of the effect in the specification covers all of the specific concepts of the claim. When responding to a ground for rejection, we review the difficulty of the technical configuration and the effect separately. For questions about claims and specifications for selection inventions in Korea, please write to contact@defineip.kr.

Sources

1. Patent Act (특허법), Act No. 21134, in force from 11 November 2025. Art. 29(1) and (2), Art. 42(3), Art. 62, Art. 87(3), Art. 132-2(1) and (2), Art. 133(1). https://www.law.go.kr/법령/특허법 (verified 9 October 2026)
2. Ministry of Intellectual Property (지식재산처), Patent Examination Guidelines (특허·실용신안 심사기준), MOIP Established Rule No. 7, in force from 13 March 2026. Part III, Chapter 2, 4.4(1); Part III, Chapter 3, 6.4.1; Part III, Chapter 3, 9(4). https://www.law.go.kr/행정규칙/특허·실용신안심사기준 (verified 9 October 2026)
3. Supreme Court Decision 2001Hu2740 Decided April 25, 2003 (대법원 2003. 4. 25. 선고 2001후2740 판결). https://www.law.go.kr/판례/(2001후2740) (verified 9 October 2026)
4. Supreme Court Decision 2008Hu736, 743 Decided October 15, 2009 (대법원 2009. 10. 15. 선고 2008후736, 743 판결). https://www.law.go.kr/판례/(2008후736) (verified 9 October 2026)
5. Supreme Court Decision 2005Hu3338 Decided September 6, 2007 (대법원 2007. 9. 6. 선고 2005후3338 판결). https://www.law.go.kr/판례/(2005후3338) (verified 9 October 2026)
6. Supreme Court Decision 2008Hu3469, 3476 Decided March 25, 2010 (대법원 2010. 3. 25. 선고 2008후3469, 3476 판결). https://www.law.go.kr/판례/(2008후3469) (verified 9 October 2026)
7. Supreme Court Decision 2010Hu3424 Decided August 23, 2012 (대법원 2012. 8. 23. 선고 2010후3424 판결). https://www.law.go.kr/판례/(2010후3424) (verified 9 October 2026)
8. Supreme Court Decision 2012Hu3664 Decided May 16, 2014 (대법원 2014. 5. 16. 선고 2012후3664 판결). https://www.law.go.kr/판례/(2012후3664) (verified 9 October 2026)
9. Supreme Court Decision 2019Hu10609 Decided April 8, 2021 (대법원 2021. 4. 8. 선고 2019후10609 판결). https://www.law.go.kr/판례/(2019후10609) (verified 9 October 2026)
10. Supreme Court Decision 2020Hu11738 Decided February 2, 2023 (대법원 2023. 2. 2. 선고 2020후11738 판결). https://www.law.go.kr/판례/(2020후11738) (verified 9 October 2026)
11. Supreme Court Decision 2002Hu1935 Decided October 24, 2003 (대법원 2003. 10. 24. 선고 2002후1935 판결). https://www.law.go.kr/판례/(2002후1935) (verified 9 October 2026)
12. EPO, Guidelines for Examination in the EPO, April 2026 edition (in force from 1 April 2026), G-VI 7 and G-VII 12. https://www.epo.org/en/legal/guidelines-epc/2026/g_vi_7.html (verified 9 October 2026)
13. USPTO, Manual of Patent Examining Procedure, 2131.02 [R-07.2022] and 2144.08 [R-01.2024]. https://www.uspto.gov/web/offices/pac/mpep/s2131.html (verified 9 October 2026)
14. Supreme Court Decision 2021Hu10022 Decided May 30, 2024 (대법원 2024. 5. 30. 선고 2021후10022 판결). https://www.law.go.kr/판례/(2021후10022) (verified 9 October 2026)