December 2025
The Supreme Court’s Clarification on the Application of the Could-Would Test in Assessing the Inventive Step: A Preliminary Analysis of Supreme Court Civil Judgment 113 Tai-Shang-Tzu No. 459 (Taiwan)
I. The Meaning of the Could-Would Test and Its Practical Application
In the battlefield of patent litigation, the “inventive step” is often the decisive factor in determining a patent’s validity. Under Article 22, paragraph 2 of the Patent Act, an invention is not patentable if it could be easily accomplished by a person having ordinary skill in the art based on prior art existing before the filing date. To prevent adjudicators from falling into the trap of “hindsight bias”, judicial practice has developed the “Could-Would” test (not simply could, but would).
Put simply, “Could” refers to “objective capability”: whether a person having ordinary skill in the art objectively possesses the technical ability to complete the invention in question in theory, based on the disclosures of the prior art. “Would,” by contrast, concerns “subjective motivation”: whether, in light of the technical context at the relevant time, such a person would have had concrete and reasonable incentives to actually undertake the research and development efforts necessary to complete the invention.
Where technical feasibility alone exists (Could), but no reasonable motivation to pursue the invention can be identified (Would), it would be inappropriate to conclude outright that the invention lacks an inventive step.
In the past, a limited number of fact-finding court judgments in Taiwan have made reference to the Could–Would test. [1] However, in Supreme Court Civil Judgment 113 Tai-Shang-Tzu No. 459, the Supreme Court expressly articulated the specific analytical steps for applying the Could-Would test, rendering the decision particularly instructive and worthy of close attention.
II. Guidance Provided by Supreme Court Civil Judgment 113 Tai-Shang-Tzu No. 459 on the Application of the Could-Would Test
The case arose from a patent infringement action in which the defendant challenged the patent in dispute on the ground that it lacked an inventive step and was therefore invalid. The patent in dispute had twice been held invalid by fact-finding courts, which reasoned that it could be “easily combined” from existing cited references and thus lacked inventiveness. [2]
In response, the Supreme Court, in its Civil Judgment 113 Tai-Shang-Tzu No. 459, once again vacated the lower court judgment and remanded the case, while at the same time articulating concrete guidance on how the Could-Would test should be applied in practice:
1. The court must first identify the “closest prior art” (i.e., the primary cited reference) and compare it with the claimed patent. Only then may the court, through the following review principles and steps (① to ⑤), objectively distinguish between the Could and Would aspects of the test.
2. Review principles and analytical steps: Whether an invention satisfies the requirement of inventive step must be assessed through a comparison with the prior art, following the established principles of inventive-step analysis, namely holistic assessment, combination analysis, and item-by-item review. Taking as the starting point “the problem the invention seeks to solve” and “the technical means for solving the problem”, the analysis should proceed as follows:
① Determine the scope of the claimed invention;
② Identify the disclosures of the relevant prior art;
③ Ascertain the level of technical skill of a person having ordinary skill in the art in the relevant technical field;
④ Identify the differences between the claimed invention and the disclosures of the relevant prior art; and
⑤ Determine whether, in light of the disclosures of the relevant prior art and the existing technology or knowledge prior to the filing date, a person having ordinary skill in the art could have easily completed the claimed invention.
In the specific application of a case, the individual elements or steps of an invention must not be isolated or disassembled in a vacuum and then mechanistically combined or pieced together against the prior art.
3. Distinguishing the Could-Would test: In assessing whether a person having ordinary skill in the art could have easily completed the invention based on the prior art, it is essential to distinguish between being “clearly willing to attempt” and being “clearly willing to carry out” the invention. The inquiry is not limited to whether the invention could theoretically be implemented with success; it must also examine whether, in the specific circumstances of the case, there existed incentives, concrete factual bases, or encouragements that would have prompted such a person to actually undertake the research and development and to successfully complete the invention.
III. Implications of This Supreme Court Judgment for Practical Litigation Strategy
For patentees, when confronted with challenges alleging a lack of inventive step, the response should not be confined to rebutting technical differences alone. They may further rely on this Supreme Court Judgment to argue that the application of the Could-Would test requires, as a preliminary matter, the identification of the closest prior art, followed by a step-by-step analysis. In particular, the invalidation requester or infringer should bear the burden of demonstrating that, at the time of filing, a person having ordinary skill in the art had a concrete motivation to combine the prior art.
Conversely, for parties seeking to challenge patent validity, this decision underscores that the judicial standard has become more clearly defined. It is no longer sufficient to merely juxtapose the technical features of the prior art with those of the patent in dispute and conclude that the invention could have been easily completed. Rather, the challenger must further provide a concrete showing, based on the technical context, industry needs, and related circumstances existing prior to the filing date, that a “subjective motivation” existed which would have prompted a person having ordinary skill in the art to undertake the research and development and bring the invention to fruition.
[1] Judgment 100 Min Zhuan Shang Yi Zi No. 10, Judgment 100 Min Zhuan Shang Yi Zi No. 8, Judgment 100 Min Zhuan Shang Yi Zi No. 12, Judgment 100 Min Zhuan Shang Yi Zi No. 22, and Judgment 100 Min Zhuan Shang Yi Zi No. 25.
[2] The court of first instance dismissed the plaintiff’s action on the ground that the combination of the cited references was sufficient to establish that the patent in dispute lacked an inventive step (Judgment 106 Min Zhuan Su Zi No. 1, Judgment 107 Min Zhuan Shang Zi No. 23). Upon the patent holder’s appeal, the Supreme Court vacated and remanded the judgment, reasoning, inter alia, that the lower court had failed to determine the level of technical skill of a person having ordinary skill in the art (Judgment 111 Tai-Shang-Tzu No. 186). In the subsequent remand proceedings, however, the court of fact adhered to its original view and again held that the claims of the patent in dispute lacked an inventive step, on the basis that certain evidence constituted prior art and could be easily combined by a person having ordinary skill in the art (Judgment 111 Min Zhuan Shang Geng Yi Zi No. 11).
In the battlefield of patent litigation, the “inventive step” is often the decisive factor in determining a patent’s validity. Under Article 22, paragraph 2 of the Patent Act, an invention is not patentable if it could be easily accomplished by a person having ordinary skill in the art based on prior art existing before the filing date. To prevent adjudicators from falling into the trap of “hindsight bias”, judicial practice has developed the “Could-Would” test (not simply could, but would).
Put simply, “Could” refers to “objective capability”: whether a person having ordinary skill in the art objectively possesses the technical ability to complete the invention in question in theory, based on the disclosures of the prior art. “Would,” by contrast, concerns “subjective motivation”: whether, in light of the technical context at the relevant time, such a person would have had concrete and reasonable incentives to actually undertake the research and development efforts necessary to complete the invention.
Where technical feasibility alone exists (Could), but no reasonable motivation to pursue the invention can be identified (Would), it would be inappropriate to conclude outright that the invention lacks an inventive step.
In the past, a limited number of fact-finding court judgments in Taiwan have made reference to the Could–Would test. [1] However, in Supreme Court Civil Judgment 113 Tai-Shang-Tzu No. 459, the Supreme Court expressly articulated the specific analytical steps for applying the Could-Would test, rendering the decision particularly instructive and worthy of close attention.
II. Guidance Provided by Supreme Court Civil Judgment 113 Tai-Shang-Tzu No. 459 on the Application of the Could-Would Test
The case arose from a patent infringement action in which the defendant challenged the patent in dispute on the ground that it lacked an inventive step and was therefore invalid. The patent in dispute had twice been held invalid by fact-finding courts, which reasoned that it could be “easily combined” from existing cited references and thus lacked inventiveness. [2]
In response, the Supreme Court, in its Civil Judgment 113 Tai-Shang-Tzu No. 459, once again vacated the lower court judgment and remanded the case, while at the same time articulating concrete guidance on how the Could-Would test should be applied in practice:
1. The court must first identify the “closest prior art” (i.e., the primary cited reference) and compare it with the claimed patent. Only then may the court, through the following review principles and steps (① to ⑤), objectively distinguish between the Could and Would aspects of the test.
2. Review principles and analytical steps: Whether an invention satisfies the requirement of inventive step must be assessed through a comparison with the prior art, following the established principles of inventive-step analysis, namely holistic assessment, combination analysis, and item-by-item review. Taking as the starting point “the problem the invention seeks to solve” and “the technical means for solving the problem”, the analysis should proceed as follows:
① Determine the scope of the claimed invention;
② Identify the disclosures of the relevant prior art;
③ Ascertain the level of technical skill of a person having ordinary skill in the art in the relevant technical field;
④ Identify the differences between the claimed invention and the disclosures of the relevant prior art; and
⑤ Determine whether, in light of the disclosures of the relevant prior art and the existing technology or knowledge prior to the filing date, a person having ordinary skill in the art could have easily completed the claimed invention.
In the specific application of a case, the individual elements or steps of an invention must not be isolated or disassembled in a vacuum and then mechanistically combined or pieced together against the prior art.
3. Distinguishing the Could-Would test: In assessing whether a person having ordinary skill in the art could have easily completed the invention based on the prior art, it is essential to distinguish between being “clearly willing to attempt” and being “clearly willing to carry out” the invention. The inquiry is not limited to whether the invention could theoretically be implemented with success; it must also examine whether, in the specific circumstances of the case, there existed incentives, concrete factual bases, or encouragements that would have prompted such a person to actually undertake the research and development and to successfully complete the invention.
III. Implications of This Supreme Court Judgment for Practical Litigation Strategy
For patentees, when confronted with challenges alleging a lack of inventive step, the response should not be confined to rebutting technical differences alone. They may further rely on this Supreme Court Judgment to argue that the application of the Could-Would test requires, as a preliminary matter, the identification of the closest prior art, followed by a step-by-step analysis. In particular, the invalidation requester or infringer should bear the burden of demonstrating that, at the time of filing, a person having ordinary skill in the art had a concrete motivation to combine the prior art.
Conversely, for parties seeking to challenge patent validity, this decision underscores that the judicial standard has become more clearly defined. It is no longer sufficient to merely juxtapose the technical features of the prior art with those of the patent in dispute and conclude that the invention could have been easily completed. Rather, the challenger must further provide a concrete showing, based on the technical context, industry needs, and related circumstances existing prior to the filing date, that a “subjective motivation” existed which would have prompted a person having ordinary skill in the art to undertake the research and development and bring the invention to fruition.
[1] Judgment 100 Min Zhuan Shang Yi Zi No. 10, Judgment 100 Min Zhuan Shang Yi Zi No. 8, Judgment 100 Min Zhuan Shang Yi Zi No. 12, Judgment 100 Min Zhuan Shang Yi Zi No. 22, and Judgment 100 Min Zhuan Shang Yi Zi No. 25.
[2] The court of first instance dismissed the plaintiff’s action on the ground that the combination of the cited references was sufficient to establish that the patent in dispute lacked an inventive step (Judgment 106 Min Zhuan Su Zi No. 1, Judgment 107 Min Zhuan Shang Zi No. 23). Upon the patent holder’s appeal, the Supreme Court vacated and remanded the judgment, reasoning, inter alia, that the lower court had failed to determine the level of technical skill of a person having ordinary skill in the art (Judgment 111 Tai-Shang-Tzu No. 186). In the subsequent remand proceedings, however, the court of fact adhered to its original view and again held that the claims of the patent in dispute lacked an inventive step, on the basis that certain evidence constituted prior art and could be easily combined by a person having ordinary skill in the art (Judgment 111 Min Zhuan Shang Geng Yi Zi No. 11).
