After a patentee obtains a patent upon publication, the patentee has a right to file a request for amending the description, scope of claims, or drawings. Therefore, in patent infringement litigation, once the accused infringer proposes any prior art reference that is sufficient to prove the patent at issue does not have patentability, the patentee may make a request to the Intellectual Property Office for a post-grant amendment of the patent during the litigation proceedings in order to overcome the defect of the validity of the patent. At the same time, according to Article 32 of the Intellectual Property Case Adjudication Rules, except where the amendment application should obviously not be granted, or if the amended scope of claim, once approved, does not constitute an infringement of right, the court shall take the extent to which the amendment has proceeded into account, and conduct the trial.

However, where a patentee requests the court to conduct the trial based on the amended claim of the patent, whether it constitutes the change of litigation claim in the Code of Civil Procedure, or only a supplement to the means of attack and defense, there are different opinions in practice.

The so-called litigation claim refers to the legal relationship of substantive law arising from the claim and specific transaction or occurrence proposed by the plaintiff and judged by the court. Therefore, the rights asserted based on different transactions or occurrences are different litigation claims (refer to the Supreme Court 2016-Tai-Shan No. 702 Civil Judgment). Once acknowledged as a change to the litigation claim, according to the provision of the Code of Civil Procedure, the plaintiff may not arbitrarily change his/her claim after the service of the complaint, except otherwise agreed upon by the defendant, or in case the specific circumstances stipulated by law (e.g. where the asserted basic fact is based on the same transaction or occurrence; or where only the claim subject to judgment is expanded or reduced). Therefore, the differentiated benefit between the change of the litigation claim or supplement of means of attack and defense, is the different provisions and standards for the acknowledgement of legitimacy.

In practice, there is an opinion holding that, based on the fact that each claim of a patent can be independently claimed as the basis of right and is the important foundation for the determination of the validity of a patent, infringement and calculation of damages, once the claim is amended, the basic fact for the determination of the court will be changed. Therefore, such amendment shall be deemed as a change of litigation claim. This opinion was adopted by the Intellectual Property Court 2015 Min-Chuan-Shang-Geng (1) No. 7, 2012 Min-Chuan-Shang No. 28, and 2010 Min-Chuan-Shang No. 12 Civil Judgments.

However, more practical judgment held that the post-grant amendment of a patent proposed by a patentee is merely one of the common means of defense for disputing the validity of the patent. Therefore, the IP Court mostly allows a patentee to amend the claim during the litigation procedure. When the IP Court determines that the post-grant amendment application shall be approved, it will then determine the patent validity and infringement issue based on the amended claim to protect the patentee's opportunity to defend his/her patent through the post-grant amendment.

Recently, the Intellectual Property Court focused on this issue and clearly held in the 2017 Min-Chuan-Shang No. 17 Civil Judgment that the content of the patent post-grant amendment belongs to the narrowing down of the scope of claim, deletion of claim, and correction of errors, which shall be included in the scope of the original claim and shall not be deemed as a change of litigation claim, but only an amendment of the fact and a supplement to the original means of attack and defense.

In light of this, given that filing a request for a patent post-grant amendment, except for correction of translation errors, shall not extend beyond the scope of the content disclosed in the description, claim, or drawing, once the patent post-grant amendment meets the legal requirements, in practice, the court tends to acknowledge that it shall be deemed a supplement to the means of defense but not a change of litigation claim.