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The Role of "Closest Prior Art" in Determining Non-Obviousness

Hsiu-Ru Chien/Alfred Lu

Non-obviousness of a claimed invention is generally determined, based on comparing the claimed subject matter with a combination of multiple prior art references cited, by investigating whether a person having ordinary skill in the art is motivated to combine the disclosure of said prior art references and can easily accomplish the claimed invention. However, there is no specific regulation in the Guidelines for Patent Examination or from court cases in Taiwan as to whether there is any priority in the application of said prior art references.
Europe, Japan and China have introduced the concept of "closest prior art" (or "principal reference") to the examination of invention patents. For instance, the Case Law of the Boards of Appeal of the European Patent Office points out: When considering whether or not claimed subject matter constitutes an obvious solution to an objective technical problem, the question to be answered is whether or not a skilled person, when solving the problem, would have modified the teaching in the closest prior art document in light of other teachings in the prior art so as to arrive at the claimed invention.
The Taiwan Intellectual Property Court (hereinafter the "IP Court") once mentioned the concept of "closest prior art" in its 2010-Min-Zhuan-Shang-No.55 judgment delivered on July 28th, 2011. According to the IP Court, the cited prior art differs from the utility model sought to be patented merely in subtle structural changes (i.e. the "closest prior art") and the distinguishing features have already been disclosed in other prior art documents of the same field to the extent that would lead a person skilled in the art to achieve the utility model sought to be patented and to realize expected functions by replacing or changing the disclosure of said closest prior art; therefore, it could be concluded that the utility model sought to be patented can be easily achieved by a person skilled in the art and thereby lacks non-obviousness.
The IP Court further defined "closest prior art" in its 2016 Xing-Zhuan-Su-No.13 administrative judgment delivered on November 21st, 2016. Based on a combination of Evidence 2 and Evidence 3 supporting the patent invalidation action, the Intellectual Property Office (IPO) concluded that the disputed patent lacked non-obviousness and thus announced to invalidate the disputed patent. During the administrative litigation proceedings, the patentee (i.e. the plaintiff) elaborated on the differences between Evidence 3 and Evidence 2 as well as the differences between Evidence 3 and the disputed patent in structure and manufacturing process, claiming they could not be easily combined.
According to the IP Court, when determining the non-obviousness of a claimed invention, the first step is to confirm the "closest prior art" and then to ascertain the differences between said invention and said closest prior art in order to determine whether or not the claimed invention is able to overcome technical problems not resolved by the prior art or to propose any inventive technical means better benefiting the industry or satisfying consumer market demands. The final step is to judge in a comprehensive manner whether or not a person having ordinary skill in the art would be motivated by reasonable and specific reasons to make the claimed invention as a whole and realize expected functions by diverting, replacing or changing the closest prior art, or combining it with other prior art references.
Based on the abovementioned opinion, the IP Court held that since the structure and manufacturing process of the disputed patent had been disclosed by Evidence 2, the prior art closest to the disputed patent, no excessive efforts should be made to mechanically compare structural differences between Evidence 3 and Evidence 2 in order to negate a possible combination of the two items of evidence in determining whether or not they can prove non-obviousness of the disputed patent. In addition, since Evidence 2 and Evidence 3 belong to relevant technical fields and aim to achieve the same technical functions by resolving technical problems with the same technical means, all these facts provide the motivation to combine the two. Moreover, the combination of the two pieces of evidence has already revealed all technical features of the disputed patent. Therefore, the IP Court negated the non-obviousness of the disputed patent and rejected the complaint of the plaintiff.
On the basis of the abovementioned judgment, it can be concluded that should the "closest prior art" have been determined and various prior art references have the potential to be combined, efforts should only be directed to confirming whether or not other prior art references used in combination have disclosed distinguishing technical features differing from the "closest prior art" and the disputed patent. No excessive efforts should be made to mechanically compare structural differences among various prior art references in order to negate their possible combinations.