In Taiwan, an application for a utility model patent only needs to pass a formality examination by the Intellectual Property Office (IPO) to be granted a patent certificate. This process offers the advantages of lower fees and expedited grant of patent. However when the patentee of a utility model patent that has not gone through substantive examination asserts patent infringement against others, the patent will be vulnerable to strong challenge to its validity, compelling the patentee to assess the patent for defects, and potentially apply for post-grant amendment.

The IPO recently issued Examination Guidelines (hereinafter referred to as "Guidelines") regarding post-grant amendment of utility model patents, which are formulated essentially based on current IPO practice. The fundamental principle spelled out in the Guidelines is: "The post-grant amendment of a utility model patent should, in principle, be subject to formality examination; only when the procedure of a cancellation action is combined with the procedure of the post-grant amendment shall substantive examination apply." Since a utility model patent is granted following formality examination only, the IPO does not need to conduct substantive examination in the procedure of post-grant amendment for a utility model patent.

The formality examination conducted in a post-grant amendment procedure for a utility model patent entails examining whether the amendment apparently extends beyond the scope of claims or drawings disclosed in the patent publication. In addition, Article 120 of the Patent Act, to which Paragraph 1, Article 67 of the Act applies mutatis mutandis, provides that post-grant amendment is limited to deletion of claims, narrowing the scope of claims, correction of errors or translation errors, and clarification of ambiguous statements. However it should be noted that:

  1. In the formality examination of post-grant amendment to claims, the amended claims are compared claim by claim with the published claims of a granted patent in terms of the actual words in the claims and the meaning which can be unambiguously understood from the words (instead of comparing the amended claims with the published drawings or descriptions in the specification).
  2. In the formality examination of post-grant amendment to drawings, the amended drawings are compared with the contents or forms which can be unambiguously understood from the published drawings of the granted patent.
  3. In the formality examination of post-grant amendment to descriptions in a patent specification, the amended description is compared with the actual text or form indicated or shown in the published claims or drawings of the granted patent, not the published descriptions in the specification of that granted patent.

For example, a patentee applies to incorporate independent claim 4 of his/her granted patent into independent claim 1 to come up with a new claim 1, which thereby results in changes to the substantial contents of claim 2 and claim 3, both of which originally depend from claim 1. Though such amendment should be allowed in the post-grant amendment of an invention patent, which is subject to substantive examination, in the post-grant amendment procedure for a utility model patent which is subject to formality examination, when the IPO compares the amended claims 1 to 3 with the published claims 1 to 3 and finds that the amended claims have additional technical features which are not specified in the text of the original claims 1 to 3, the IPO will reject the post-grant amendment because it "apparently extends beyond the originally granted scope in formality." Because the content of a patent specification does not form the basis for comparison conducted by the IPO in the formality examination of the post-grant amendment for a utility model patent, it is suggested that the claims of a utility model patent be drafted to include as many implementable embodiments as possible to facilitate post-grant amendment in the future.

Since the formality examination of post-grant amendment for a utility model patentconducted by the IPO is based on rigorous comparison as explained above, if significant amendment to a patent may be needed in order to obtain a reasonable and valid scope of claims (and/or drawings, description), the patentee may need to have the IPO conduct a substantive examination procedure for the amendment. One approach is to apply for patent amendment in response to an ongoing cancellation action procedure. However under local practice, the IPO does not accept a cancellation action filed by the patentee him/herself. If there is no cancellation action coincidentally filed by a third party, the patentee may have to privately authorize a third party to file a cancellation action in that third party's name. After the IPO accepts the cancellation action request and starts the procedure, the patentee can apply for post-grant amendment in the proceeding in response to the cancellation action. In the cancellation action, the IPO will adopt "substantive examination" of the post-grant amendment according to the same Guidelines for the examination of post-grant amendment to an invention patent.  

As mentioned above, though a post-grant amendment filed for a utility model patent could be rejected by the IPO under formality examination, a different decision could be rendered under substantive examination. Thus a patentee can apply for the same post-grant amendment in a cancellation action procedure as filed before in a formality examination procedure, and the IPO will conduct substantive examination for the post-grant amendment as well as the cancellation action.