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Restricting the scope of claims by introducing disclaimers in Taiwan


Chiu-ling Lin of Saint Island International Patent & Law Offices explores recent clarifications by Taiwan’s IP Office in relation to the use of disclaimers

Under international practice, it is in principle, acceptable to file an amendment or post-grant amendment by the introduction of a ‘disclaimer’. This is possible when considered from the perspective of an ordinary person skilled in the art, the subject-matter remaining in the claims after amendment is seen to be directly and unambiguously derivable from the application as filed.

As to ‘undisclosed disclaimers’, in some major jurisdictions like the European Union or Japan, the scope of a claim can be so restricted only in the case where an application or patent faces a ‘lack-of-novelty’ or ‘lack-of-fictitious novelty’ rejection/challenge, or is not directed to a ‘statutorily patentable subject-matter’. On the other hand, there is no way to overcome the ‘lack-of-obviousness’ rejection/challenge by excluding a claim amendment or post-grant amendment, a technical feature disclosed or suggested in the prior art.

An excluded feature generally cannot derive from the specification, claims or drawings of a patent application, as filed in a direct and unambiguous manner. Therefore, it is set out in Section 2, Chapter VI of Taiwan’s Patent Examination Benchmark that restricting the scope of a claim by the introduction of a ‘disclaimer’ is not allowed lest that new matter should be added.

The only exception to this rule applies if and when it is not possible whatsoever to define a technical feature clearly and concisely in a positive manner. Given that it is not clearly set out in the examination benchmark, the conditions under which the scope of a claim may be restricted by the introduction of ‘disclaimer’, and has become a grey area which is open to wide interpretation and may potentially lead to an abusive use of ‘disclaimer’. Taiwan’s IP Office (TIPO) subsequently made a rectification by publishing an announcement on its website on November 19 2020.

The announcement specifies that an ‘undisclosed disclaimer’ is only allowed in a claim amendment or post-grant amendment to:

  1. Restore novelty against a prior art under Article 22(1) of the Taiwan Patent Act;

  2. Restore novelty against an application earlier filed but later published in Taiwan under Article 23;

  3. Comply with the first-to-file doctrine under Article 31(1), which is however not applicable when the patent application and the prior art carry the same filing date; and

  4. Exclude subject-matter that is statutorily unpatentable, including: 

  • Disclaim a portion of a product claim relating to ‘human beings’; and

  • Disclaim a portion of a method claim relating to the processing steps performed on ‘human and animal bodies’. 

Moreover, in reply to an enquiry from the Association of Patent Attorneys, TIPO issued a letter of explanation clarifying as follows: 

  1. The amended rules regarding ‘disclaimers’ were formulated with an attempt to cure the deficiency and ambiguity in the examination benchmark by referencing the international practice and findings from relevant cases. No additional norms were included in the benchmark.

  2. In assessing ‘obviousness’ as opposed to ‘novelty’, multiple sources of prior art may be applied and various factors ought to be taken into account, such as the relatedness of and distinctions between the claimed invention and the cited prior art, and also the achievability of the invention by an ordinary person skilled in the art based on the teachings in cited prior art. As it is rather difficult to accurately interpret the scope of a claim with a disclaimer, for avoidance of unnecessary controversy, revising claims to an extent necessary to overcome a ‘lack-of-obviousness’ rejection/challenge by the introduction of ‘disclaimer’ should not be permitted. 

  3. If a ‘lack-of-obviousness’ rejection/challenge is raised during prosecution or in an invalidation action with one single prior art reference being cited, and if the applicant believes the cited prior art is actually competent to challenge the novelty of the invention and the novelty can be restored by revising claims with a disclaimer, they may file a response with justifiable reasons, accompanied by a claim amendment. 

Notwithstanding TIPO’s announcement and explanation as reported above, since restricting the claim scope by the introduction of either a disclosed or undisclosed disclaimer would unavoidably face inherent uncertainty, the applicant is still advised to disclose their invention in the specification and drawings as fully and completely as possible. This is to provide a sufficient basis to revise claims at a later time, if necessity arises.

Chiu-Ling Lin

Patent attorney, Saint Island International Patent & Law Offices


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