After a patent has been granted by the patent office, anyone who considers it to lack novelty or inventive step can file a cancellation (invalidation) action along with the relevant prior art references. In some countries, the patentability issues that may be submitted to the patent office for re-examination during the cancellation action cannot overlap those examined substantially at the patent application stage. However, there is no such regulation in Taiwan.

If a prior art reference submitted by a cancellation petitioner in a cancellation action is one that the patent office has substantially reviewed and compared with the patented technique, can the patent office depart from its original conclusion to decide that some claims of that patent do not have an inventive step over the same prior art reference?


With regard to this potentially contentious issue, the Supreme Administrative Court (2014-Pan-242, May 15 2014) and the IP Court (2013-Xing-Zhuan-Su-50, October 9 2013) have both rendered for a cancellation case and appear to accept that the patent office can adopt different opinions in a patent application and cancellation action.

The patent involved in the cancellation cases related to a hand tool. At the application stage, the patent office issued an office action mentioning that Citation A rendered all claims obvious (non-inventive) to persons with ordinary skill and requested that the applicant respond and amend the claims. The applicant responded with a claim amendment and an explanation regarding the differences between the invention and Citation A. After examining the amended claims, the patent office granted the patent. A third party then filed a cancellation action against some claims of the patent based on Citation A. The patent office agreed with the cancellation petitioner's arguments and concluded that Citation A substantially disclosed the elements and structure recited in the claims, which was sufficient to prove that the claims lacked inventive step. The patent office also mentioned that the combination of Citation A and the prior art described in the specification of the target patent further proved that the patent lacked inventive step. The patent right was therefore withdrawn.The patentee filed an administrative suit with the IP Court, arguing that the patent office had violated the principle of good faith in administrative behaviours and had failed to give reasons in its cancellation decision in view of the facts that the patent office had reversed its conclusion at the application stage without explanation.

The IP Court affirmed the patent office's decision for the cancellation action. It stated that all technical features in the claims had been substantially disclosed by Citation A, and that any minor modification in shape could be understood directly by persons in the art with reference to the description in the prior art section of the specification of the target patent. The Supreme Administrative Court drew the same conclusion.


The IP Court and the Supreme Administrative Court both agreed that the patent office cited "the description regarding the prior art in the field in the specification of the target" as prior art and combined it with Citation A to negate the inventive step of the patent. This is consistent with a previous Supreme Administrative Court judgment (2012-Pan-774), in which the court pointed out that "the rule of estoppel and the principle of good faith are also applicable in cases pertaining to patent validity". That is, where a patentee clearly indicates in the patent specification that a patent or technique is prior art, that should be deemed a qualified prior art reference without requiring proof when the patent's validity is further evaluated. This is to ensure consistency of the patentee's explanations regarding the invention and to protect not only the interests of the cancellation petitioner, but also the interest of the public. Such interests are formed on the basis that the public believes the patentee's previous explanations and statements. The judgments imply that the prior art mentioned in a patent specification is a qualified prior art reference and can be combined with other prior art references to challenge the patent's validity in a cancellation action. Such opinion would significantly reduce a cancellation petitioner's burden of proof on admissibility of evidence. With this in mind, a patent applicant must consider carefully whether and how to disclose a skill or technique used before the invention to be claimed in a patent specification.

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

This article was first published by the International Law Office, a premium online legal update service for major companies and law firms worldwide. Register for a free subscription.