The non-obviousness of a claimed invention is generally determined – based on comparing the claimed subject matter with a combination of multiple prior art references – 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 example, 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 IP Court mentioned the concept of 'closest prior art' in its 2010 Min-Zhuan-Shang-No 55 judgment of July 28 2011. According to the court, the cited prior art differs from the utility model sought to be patented merely in subtle structural changes (ie, 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 a person skilled in the art could achieve the utility model sought to be patented and realise the 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 Taiwan IP Court further defined 'closest prior art' in its 2016 Xing-Zhuan-Su-No 13 administrative judgment delivered on November 21 2016. Based on a combination of Evidence 2 and Evidence 3 supporting the patent invalidation action, the Intellectual Property Office concluded that the disputed patent lacked non-obviousness and therefore announced to invalidate the disputed patent. During the administrative litigation proceedings, the patentee (the plaintiff) elaborated on the differences between Evidence 2 and Evidence 3 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 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 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 comprehensively judge whether 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 realise its expected functions by diverting, replacing or changing the closest prior art or combining it with other prior art references.

Based on this, the Taiwan 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 2 and Evidence 3 in order to negate a possible combination of the two items of evidence in determining whether they can prove non-obviousness of the disputed patent. Further, 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 of 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 court negated the non-obviousness of the disputed patent and rejected the complaint of the plaintiff.

On the basis of this 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 be directed only to confirming whether 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.

For further information on this topic please contact Hsiu-Ru Chien or Alfred Lu at Lee and Li Attorneys at Law by telephone (+886 2 2715 3300) or email ([email protected] or [email protected]). The Lee and Li Attorneys at Law website can be accessed at