As a material principle of determining patent infringement, the “doctrine of equivalents” is designed to protect a patentee’s interests in a manner that prevents others from circumventing liabilities arising from potential patent infringement committed by making insubstantial changes to technical means claimed in the claims of the patent in question. To be specific, the “doctrine of equivalents” aims to overcome linguistic limitations of a claim because the scope of a patent is not limited to the “literal scope” defined in claims but may moderately extend to an “equivalent scope”.

According to judicial practices in Taiwan,the “triple identity test” or “tripartite test” is generally adopted to determine whether the technical content of the infringing subject is equivalent to the technical characteristics claimed in the claims of the patent in question when they literally differ from each other. In other words, if both the technical content of the alleged infringing subject and the technical characteristics claimed in the claims of the patent in question employ substantially the same way to implement substantially the same function so as to achieve substantially the same result, it should be concluded that the two possess no substantial difference and thereby are equivalents.

During the actual application of the “doctrine of equivalents”, disputes usually arise from the determination of “substantially the same”, which is an indefinite legal concept. On 5 February 2016, the Taiwan Intellectual Property Office (TIPO) of the Ministry of Economic Affairs published the “Procedures of Patent Infringement Determination” (hereinafter the “Procedures”) upon substantial amendments. In the Procedures, the principle of determining “substantially the same” under the “doctrine of equivalents” is defined as follows: “‘Substantially the same’ refers to such an extent of difference between the patented invention in question and the infringing technology that can be easily accomplished by a person having ordinary skill in the art (PHOSITA) or is obvious to a PHOSITA.” It seems that the TIPO is referencing the general criteria for determining the “inventive step” (whether or not such can be easily accomplished or is obvious). Should any doubt arise from telling them apart, hints can be found in the 2017-Tai-Shang-Zi-No.585 verdict newly delivered by the Supreme Court of Taiwan on 24 April 2017.

In this case, the alleged infringer claimed that the questioned product manufactured and sold by his company involves a design wherein “the lower surface of the exposed part coordinates with a slope”, and thus the “ratchet” and the “hub”, often “normally closed”, allow consumers to move the bicycle directly forward or backward and without worrying about rotating pedals during the movement. On the contrary, the patent in question involves a structural design, wherein “the protruding rod coordinates with a groove of supportive holes”, and consumers, in order to make the “ratchet” and the “hub” normally closed, have to manually rotate pedals backward so as to drive the ratchet piece backward until the protruding rod of the ratchet rotates to the inner-side of the supportive holes. Therefore, consumers have to, before moving a bicycle, rotate pedals backward by using their hands or feet to keep pedals still. The patented practice is obviously more time-consuming. The Supreme Court thereby reversed the original judgment and remanded the case back to the Intellectual Property Court of Taiwan on the grounds that the original judgment failed to explore in detail whether the difference between “the protruding rod coordinating with a groove of supportive holes” claimed in the patent in question and “the lower surface of the exposed part coordinating with a slope” applied in the questioned product can be explained by similar cam mechanisms, and whether the two designs are equivalent replacements without any substantial difference.

In its judgment, the Supreme Court ruled: “The doctrine of equivalents used in the determination of patent infringement involves whether the alleged infringing subject and the structure/process claimed in the claims of the patent in question employ substantially the same technical means to realize substantially the same functions and results. When it is easy for a PHOSITA, after reading the patent specification, especially the claims and descriptions, to come up with the alternative technical means adopted by the infringing subject and use it as a replacement based on his/her general expertise and professional experience, the infringing subject is substantially the same as the patent in question.” Although these statements roughly conform with the gist of the aforementioned Procedures, both the theoretical framework of the judgement and the defense of the alleged infringer against the doctrine of equivalents employ a reasoning methodology similar to the determination of “inventive step”. That is, the alleged infringer raised a defense by emphasizing the product in question delivers better efficiency than the patent in question and their difference cannot be easily accomplished by a PHOSITA, which, according to the alleged infringer, disqualifies the applicability of the doctrine of equivalents. The Supreme Court seems to second such reasoning methodologies.