|Defendants in a patent infringement proceeding may challenge the validity as a defense.
Otherwise, TIPO is the competent authority which can invalidate a granted patent right. According to Article 71 of the Patent Act, anyone may challenge the validity of a patent with TIPO under any of the following circumstances:
1. there is a violation of patentability, disclosure requirements, first-to-file principle, the requirements of one creation applied for invention patent and utility model patent, the limitation on divisional patent applications, the limitation on amendment, the limitation on the Chinese translation of foreign documents and the correction thereof, the limitation on post-grant amendments, or the limitation on conversion of patent applications;
2. the home country of the patentee does not accept the patent applications filed by R.O.C. nationals.
However, only an interested party can challenge the validity of a patent if the ground of invalidity is based on entitlement to patent application, namely, there is a violation of the joint application requirement, or the invention patent owner is not entitled to file the patent application.