Regarding the principle of clarity, Article 26.2 of Taiwan Patent Act stipulates that “a claim shall be clearly disclosed.” As for the clarity of terminology, the current Patent Examination Guidelines (“Examination Guidelines”) point out that “The technical terminology in the technical field to which the invention belongs shall be used. The terminology used shall be clear and comprehensible, so as to define the true meaning thereof.”
In addition, the principle that “a patentee acted as its own lexicographer” is conditionally accepted in the examination practices of many countries. Taiwan's Examination Guidelines are no exception, requiring that “specifically defined technical terminology” must not impair clarity: “Such a technical terminology may be recognized only when determined to carry no other equivalent meaning. If a technical terminology already possesses a basic meaning in its technical field, it shall not be used to express a different meaning other than its basic meaning, so as to avoid confusion.” Accordingly, whether a technical term “already possesses a basic meaning” becomes a key issue in the examination.
In this regard, a recent judgment of the Intellectual Property and Commercial Court ("IPC Court"), Judgment (2025) Xing-Zhuan-Su No. 39, rendered in July this year, provides useful insights into the above issue.
In the patent invalidation action at issue in this lawsuit, the specification of the patent-in-dispute provides its own definition of the term “permanent positive charge,” which the patentee asserts is a newly coined term, and uses “zeta potential” and “millivolts” as the subject and unit of measurement for the permanent positive charge, respectively. This led to a dispute over whether such usage violates the principle of clarity under Article 26.2 of the Patent Act.
The Taiwan Intellectual Property Office (TIPO) answered in the affirmative, whereas the Petitions and Appeals Committee (“Committee”) of the Ministry of Economic Affairs disagreed and thus revoked TIPO's ruling. As such, the Committee became the defendant in the ensuing litigation, an unusual situation in invalidation disputes. More notably, the IPC Court upheld TIPO's position.
The Committee held that “permanent,” “positive charge,” “zeta potential,” and “millivolts” each have their own basic meanings. Even if “permanent” does not refer to circumstances where no change ever occurs, it should still refer to circumstances where a substance will not change its properties under ordinary conditions, unless subjected to an extreme means. However, the specification of the patent-in-dispute merely recites that the positive charge on the particles is not readily reversible, for example, via flushing, dilution, filtration, and the like, but fails to specify under what extreme means such property would change. Therefore, it is doubtful whether those skilled in the art can clearly understand the meaning of the “permanent” positive charge from the disclosure of the specification. In addition, while the unit of measurement for “positive charge” is the “Coulomb (C),” the specification consistently uses “zeta potential” and “millivolts” as the subject and unit of measurement therefor, respectively. Moreover, “potential” and “millivolts” have their own basic meanings, which differ from “charge,” and none of them is a unit of charge. Therefore, it is also doubtful whether the use of these terms to express a “positive charge” would cause confusion, and whether those skilled in the art can clearly understand the meaning of the “permanent positive charge” from the disclosure of the specification of the patent-in-dispute.
However, the IPC Court held a different view. First, the Court pointed out that according to the principles of claim construction disclosed in the Examination Guidelines and the Patent Infringement Assessment Guidelines, if a term in a claim has been clearly defined or explained in the specification (whether it is a newly coined term or a redefined term), the claim should be construed based on that definition or explanation. Accordingly, although “permanent” and “positive charge” each have their own basic meanings, given that the patent-in-dispute has already defined “permanent positive charge” as a new parameter, this term should be viewed as a whole rather than being dissected and interpreted separately. Furthermore, the specification of the patent has provided a reasonably clear and precise specific meaning for this term, and comprehensively explained its way of expression and measurement method (how to measure the “zeta potential” or “millivolts”). The content of this term can thus be distinguished from the original meanings perceived by the general public without causing confusion. Therefore, the defendant's concerns regarding clarity are unfounded.
The judgment offers two useful takeaways for patent drafting as well as interpretation. First, patent drafters should, as far as possible, preserve the formal integrity of a specifically defined term, so that the IPC Court's approach of construing the term as a whole can be more readily applied. Second, in addition to providing a clear and precise direct definition for the new term itself, patent drafters could incorporate the applicable measurement method and unit of measurement into the definition, thereby further ensuring clarity.
This case has been appealed to the Supreme Administrative Court, and whether the Court will affirm this view remains to be seen.