06.09.2026
Preventing Hindsight Bias in Patent Non-Obviousness Determination: Legal Principles and Judicial Insights
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I. Introduction
When examining an invention patent application, the examiner first determines whether the claimed invention is disclosed by prior art. If the invention is not disclosed, it possesses novelty. Subsequently, the examiner evaluates whether the invention, despite differences from the prior art, could have been easily accomplished by a person having ordinary skill in the art (PHOSITA) to determine non-obviousness (i.e., inventive step). However, while an invention is created in view of only the prior art, the examiner conducts the examination while simultaneously having access to both the prior art and the content of the application, and this difference in perspective easily leads to divergent views regarding whether claimed inventions are non-obvious.
To address this issue, the Patent Examination Guidelines aim to prevent patent examiners and judicial authorities from retroactively re-evaluating technical problems and their solutions through the lens of the disclosed invention, thereby underestimating the extent of its progress and innovation. This article explores the application of the "hindsight bias" principle and its impact on patent examination and judicial proceedings, based on relevant judgments from the Intellectual Property and Commercial Court, the Supreme Administrative Court, and the Supreme Court.
II. Concept and Jurisprudential Basis of "Hindsight Bias"
"Hindsight bias" refers to the tendency of examiners or judges, once aware of the technical content of an invention in a patent application, to unconsciously view the invention as obvious, thereby devaluing its innovation. Patent Law emphasizes that the determination of non-obviousness should be based on the state of the art at the time of filing, rather than using hindsight to consider a solution as self-evident.
Regarding non-obviousness, Article 22, Paragraph 2 of the Patent Act stipulates: Even if an invention does not fall under any of the circumstances in the preceding paragraph, it shall not be granted an invention patent if it could have been easily accomplished by a PHOSITA based on the prior art before the date of filing. Therefore, the level of skill of the "PHOSITA," the "level of prior art," and whether the invention could have been "easily accomplished" are frequent primary points of contention between examiners and applicants.
The Patent Examination Guidelines specify that the examination of non-obviousness must not be based on "hindsight" derived from the specification, claims, and drawings. Instead, the invention as a whole should be compared with relevant prior art, and an objective judgment should be made from the perspective of a PHOSITA considering the common knowledge at the time of filing. Regarding the "motivation to combine multiple references," the Guidelines state that examiners should consider the relevance or commonality between the multiple references themselves, rather than between the references and the claimed invention, to avoid hindsight bias.
Nevertheless, examiners may still occasionally resort to "hindsight" when evaluating non-obviousness because they lack practical experience in the relevant field, thus leading to inaccurate assessments of the PHOSITA's technical level. On the other hand, due to their extensive experience in examining related fields, examiners may have previously encountered individual technical features, and since their technical expertise may exceed that of a PHOSITA, if they fail to adjust their perspective to that of a PHOSITA, they are more prone to reaching a conclusion that the invention could have been "easily accomplished."
III. Practical Insights from Court Judgments
According to Supreme Court Civil Judgment 113 Tai Shang Zi No. 459, the determination of non-obviousness should not involve simply dismantling the individual elements or steps of an invention and then mechanically comparing them with prior art references. In other words, the focus of determining non-obviousness is not merely whether execution could theoretically be successful, but whether there was an incentive, concrete factual basis, or encouragement in the specific case to prompt a skilled person to pursue and succeed in the research and development. This approach avoids a mechanical piecing together of prior art references that inevitably leads to the fallacy of hindsight.
In this regard, Judgment 112 Xing Zhuan Su Zi No. 70 of the Intellectual Property and Commercial Court further pointed out that when determining whether a PHOSITA has a motivation to combine multiple references, the relevance or commonality of the technical contents of those references should be considered, rather than the relevance between the references and the claimed creation. Generally, factors such as "relevance of technical fields," "commonality of problems to be solved," "commonality of functions or operations," and "teachings or suggestions" should be comprehensively considered. Relevance of technical fields is judged by whether the technical fields of the references are identical or related, which can be evaluated based on the objects, principles, mechanisms, or functions of the applied technology, which aligns with the Examination Guidelines' standard for determining motivation for combination.
Furthermore, Supreme Administrative Court Judgment 112 Shang Zi No. 490 states that as non-obviousness examination often involves combining multiple references, to avoid arbitrary piecing together and hindsight bias, examiners should consider whether a PHOSITA would have had the motivation to combine those references to complete the claimed invention. If such motivation exists, it may serve as a factor to negate non-obviousness. Factors to consider include relevance in the technical field, commonality of technical problems, commonality of functions/operations, and whether there are explicit or implicit teachings or suggestions for combination.
Additionally, Supreme Administrative Court Judgment 110 Shang Zi No. 597 specifies that in invalidation cases, the scope and content of prior art (evidence) should be determined first, followed by identifying differences between the subject invention and the evidence. Finally, based on the disclosure of the evidence and common knowledge at the time of filing, it is determined whether a PHOSITA could have easily accomplished the invention. Examination must not use "hindsight" derived from the description in the specification to conclude that the invention was easily accomplished; rather, the invention as a whole must be compared with the evidence to make an objective judgment.
Supreme Administrative Court Judgment 109 Shang Zi No. 356, an administrative litigation involving a patent invalidation, noted that while multiple references or portions thereof can be combined to judge non-obviousness, there must be an objective motivation for such combination. In this particular case, although all the evidence belonged to the same technical field of cooling fans, the cited prior art references were aimed at different purposes and thus lacked commonality in the problem to be solved or functions. Hence, the court concluded that the combination was a result of hindsight bias. Accordingly, if a petitioner merely cites evidence without establishing a motivation for combination based on the aforementioned four factors, obviousness cannot be established.
Based on the court judgments above, the criteria are consistent with the Patent Examination Guidelines, namely, comprehensive evaluation of "relevance of technical fields," "commonality of problems to be solved," "commonality of functions or operations," and "teachings or suggestions" is required to determine the motivation to combine references.
Furthermore, non-obviousness should not be judged through "hindsight" derived from the specification but through an objective comparison of the invention as a whole with the prior art from a PHOSITA's perspective.
The fact that there is no quantitative standard for weighing these four factors gives examiners significant administrative discretion. However, applicants can still challenge the examiner's opinion by arguing based on these four aspects to persuade the examiner.
IV. Conclusion
The identification of "hindsight bias" plays a vital role in patent examination and judicial practice to ensure that the judgment of non-obviousness is objective and reasonable, and preventing hindsight is an indispensable part of the process. Applicants, examiners, and both parties in invalidation proceedings therefore should have a profound understanding of the underlying principles to effectively navigate patent practice.
When examining an invention patent application, the examiner first determines whether the claimed invention is disclosed by prior art. If the invention is not disclosed, it possesses novelty. Subsequently, the examiner evaluates whether the invention, despite differences from the prior art, could have been easily accomplished by a person having ordinary skill in the art (PHOSITA) to determine non-obviousness (i.e., inventive step). However, while an invention is created in view of only the prior art, the examiner conducts the examination while simultaneously having access to both the prior art and the content of the application, and this difference in perspective easily leads to divergent views regarding whether claimed inventions are non-obvious.
To address this issue, the Patent Examination Guidelines aim to prevent patent examiners and judicial authorities from retroactively re-evaluating technical problems and their solutions through the lens of the disclosed invention, thereby underestimating the extent of its progress and innovation. This article explores the application of the "hindsight bias" principle and its impact on patent examination and judicial proceedings, based on relevant judgments from the Intellectual Property and Commercial Court, the Supreme Administrative Court, and the Supreme Court.
II. Concept and Jurisprudential Basis of "Hindsight Bias"
"Hindsight bias" refers to the tendency of examiners or judges, once aware of the technical content of an invention in a patent application, to unconsciously view the invention as obvious, thereby devaluing its innovation. Patent Law emphasizes that the determination of non-obviousness should be based on the state of the art at the time of filing, rather than using hindsight to consider a solution as self-evident.
Regarding non-obviousness, Article 22, Paragraph 2 of the Patent Act stipulates: Even if an invention does not fall under any of the circumstances in the preceding paragraph, it shall not be granted an invention patent if it could have been easily accomplished by a PHOSITA based on the prior art before the date of filing. Therefore, the level of skill of the "PHOSITA," the "level of prior art," and whether the invention could have been "easily accomplished" are frequent primary points of contention between examiners and applicants.
The Patent Examination Guidelines specify that the examination of non-obviousness must not be based on "hindsight" derived from the specification, claims, and drawings. Instead, the invention as a whole should be compared with relevant prior art, and an objective judgment should be made from the perspective of a PHOSITA considering the common knowledge at the time of filing. Regarding the "motivation to combine multiple references," the Guidelines state that examiners should consider the relevance or commonality between the multiple references themselves, rather than between the references and the claimed invention, to avoid hindsight bias.
Nevertheless, examiners may still occasionally resort to "hindsight" when evaluating non-obviousness because they lack practical experience in the relevant field, thus leading to inaccurate assessments of the PHOSITA's technical level. On the other hand, due to their extensive experience in examining related fields, examiners may have previously encountered individual technical features, and since their technical expertise may exceed that of a PHOSITA, if they fail to adjust their perspective to that of a PHOSITA, they are more prone to reaching a conclusion that the invention could have been "easily accomplished."
III. Practical Insights from Court Judgments
According to Supreme Court Civil Judgment 113 Tai Shang Zi No. 459, the determination of non-obviousness should not involve simply dismantling the individual elements or steps of an invention and then mechanically comparing them with prior art references. In other words, the focus of determining non-obviousness is not merely whether execution could theoretically be successful, but whether there was an incentive, concrete factual basis, or encouragement in the specific case to prompt a skilled person to pursue and succeed in the research and development. This approach avoids a mechanical piecing together of prior art references that inevitably leads to the fallacy of hindsight.
In this regard, Judgment 112 Xing Zhuan Su Zi No. 70 of the Intellectual Property and Commercial Court further pointed out that when determining whether a PHOSITA has a motivation to combine multiple references, the relevance or commonality of the technical contents of those references should be considered, rather than the relevance between the references and the claimed creation. Generally, factors such as "relevance of technical fields," "commonality of problems to be solved," "commonality of functions or operations," and "teachings or suggestions" should be comprehensively considered. Relevance of technical fields is judged by whether the technical fields of the references are identical or related, which can be evaluated based on the objects, principles, mechanisms, or functions of the applied technology, which aligns with the Examination Guidelines' standard for determining motivation for combination.
Furthermore, Supreme Administrative Court Judgment 112 Shang Zi No. 490 states that as non-obviousness examination often involves combining multiple references, to avoid arbitrary piecing together and hindsight bias, examiners should consider whether a PHOSITA would have had the motivation to combine those references to complete the claimed invention. If such motivation exists, it may serve as a factor to negate non-obviousness. Factors to consider include relevance in the technical field, commonality of technical problems, commonality of functions/operations, and whether there are explicit or implicit teachings or suggestions for combination.
Additionally, Supreme Administrative Court Judgment 110 Shang Zi No. 597 specifies that in invalidation cases, the scope and content of prior art (evidence) should be determined first, followed by identifying differences between the subject invention and the evidence. Finally, based on the disclosure of the evidence and common knowledge at the time of filing, it is determined whether a PHOSITA could have easily accomplished the invention. Examination must not use "hindsight" derived from the description in the specification to conclude that the invention was easily accomplished; rather, the invention as a whole must be compared with the evidence to make an objective judgment.
Supreme Administrative Court Judgment 109 Shang Zi No. 356, an administrative litigation involving a patent invalidation, noted that while multiple references or portions thereof can be combined to judge non-obviousness, there must be an objective motivation for such combination. In this particular case, although all the evidence belonged to the same technical field of cooling fans, the cited prior art references were aimed at different purposes and thus lacked commonality in the problem to be solved or functions. Hence, the court concluded that the combination was a result of hindsight bias. Accordingly, if a petitioner merely cites evidence without establishing a motivation for combination based on the aforementioned four factors, obviousness cannot be established.
Based on the court judgments above, the criteria are consistent with the Patent Examination Guidelines, namely, comprehensive evaluation of "relevance of technical fields," "commonality of problems to be solved," "commonality of functions or operations," and "teachings or suggestions" is required to determine the motivation to combine references.
Furthermore, non-obviousness should not be judged through "hindsight" derived from the specification but through an objective comparison of the invention as a whole with the prior art from a PHOSITA's perspective.
The fact that there is no quantitative standard for weighing these four factors gives examiners significant administrative discretion. However, applicants can still challenge the examiner's opinion by arguing based on these four aspects to persuade the examiner.
IV. Conclusion
The identification of "hindsight bias" plays a vital role in patent examination and judicial practice to ensure that the judgment of non-obviousness is objective and reasonable, and preventing hindsight is an indispensable part of the process. Applicants, examiners, and both parties in invalidation proceedings therefore should have a profound understanding of the underlying principles to effectively navigate patent practice.
