Pursuant to the Code of Civil Procedure, a plaintiff may not amend his or her statement of claim or raise additional claims after the service of the complaint unless the defendant agrees to it or the amendment or addition conforms to some specific circumstances as stipulated by law; for example, the amendment or addition of the statement of claim is based on the same transaction or occurrence, or the amendment or addition of the statement of claim is merely related to expansion or reduction of the demand for judgment for the relief sought.

Pursuant to the Intellectual Property Case Adjudication Act implemented in 2008, the accused infringers may counter the accusation by challenging the validity of the patent concerned, on which the court shall decide based on the merit of the case. To respond to the invalidation challenge, patentees often apply to the Intellectual Property Office (“IPO”) during the lawsuit for post-grant amendment and ask the court to render a decision based on the amended scope of patent claim. In practice, the Intellectual Property Court (“IP Court”) allows patentees to apply for a post-grant amendment during the proceeding, and if the post-grant amendment is deemed accepable, the IP Court will make a decision on the patent validity and infringement issues based on the amended scope of patent claim. However, there have been a few discussions on the question on whether post-grant amendment, after a patentee has filed a complaint that results in the change of content of rights, constitutes an amendment of the statement of claim in the action. An observation of the relevant judgments issued by the IP Court finds that the Court mostly treats the situation as a means of attack or defense adopted by the patentee that does not involve an amendment of the statement of claim so as to give patentees an opportunity to assert the validity of their patent through corrective defense.

However, the IP Court, in judgment No. 2012-Ming-Zhuan-Shang-Zi-28, rendered on August 2013, holds that an application for post-grant amendment by a patentee after filing an appeal constitutes an amendment of the statement of claim; if the defendant provides the same prior art references to challenge the validity of amended patent claim as those provided in the original trial, the major issues of contention after the post-grant amendment are considered the same, and the amendment or addition of the statement of claim is based on the same transaction or occurrence and may be allowed without the consent of the defendant. In this case, the Supreme Court made a third instance judgment on September 2, 2015 (No. 2015-Tai-Shang-Zi-1651), dismissing the aforementioned decision of the IP Court. But the reasons given by the Supreme Court only point out that if the second-instance court determines that it is an amendment of the statement of claim and the amendment is lawful, the patentee’s pending action in the original lawsuit no longer exists due to the amendment of the statement of claim, whereas the second-instance court may only hear the case involving the amended statement of claim and may not render a decision based on the original lawsuit rendered in the first-instance court. The Supreme Court did not express a specific view on whether a post-grant amendment filed in a pending action constitutes an amendment of the statement of claims.

As described above, in practice, the IP Court has been directly hearing cases involving post-grant amendment, and if the post-grant amendment is deemed permissible, the Court will make a decision on the patent validity and infringement issues based on the amended scope of patent claim. Based on the judgments rendered by the IP Court after the aforementioned Supreme Court decision, the IP Court has not changed its practice. However, subsequent development of court practice remains to be seen.