균등침해요건

The Doctrine of Equivalents: solution equivalent in value and identical effect

Under the Doctrine of Equivalents (hereinafter DOE ), the equivalent means must be equivalent in value and achieve the identical effect. The Supreme Court held in its 2012 Hu 1132 Decision that whether the solution of the accused embodiment is equivalent in value to the solution of the patented invention must be determined based on the essence of the invention. The Supreme Court dealt with this issue in detail in its 2017 Hu 424 Decision. Furthermore, the Supreme Court Decision 2018 Da 267252 for the first time provided the test to examine the identical effect. This article considers these DOE criteria, based on the case analysis. The positive aspect of the Court s decision is that DOE was applied to individual elements of the claim, not to the claimed invention as a whole. However, it is the negative aspect that the Court applied the equivalent in value test based not on individual comparison but on overall comparison. With this interpretation, it is difficult to combine a fair protection for the patent proprietor with a reasonable degree of legal certainty for third parties. Rather, all the criteria of DOE should be examined from two aspects: individual comparison and overall comparison. Although the Court explained how to use prior arts under the equivalent in value test, two things should be remembered. Basically, the essence of the invention shall be determined by the specification and prior arts not described in the specification shall only be considered in order to define the range of equivalence. Since the patent law protects the invention defined by the elements, not the underlying principles of the invention, it is important not to overly generalize the claimed solution. According to the Supreme Court Decision 2018 Da 267252, two different tests are applied when examining the identical effect, depending on whether or not the essence of the invention was known before the filing date. If the identical effect is examined this way, the identical effect requirement of DOE would depend a lot on the solution equivalent in value requirement of DOE and the role of the identical effect requirement would be diminished. DOE shall be applied to individual elements of the claim, not to the claimed invention as a whole. Thus, all the criteria of DOE should be examined from two aspects: individual comparison and overall comparison. When applying the solution equivalent in value test, it is important to remember that the patent law protects the invention defined by the elements, not the underlying principles of the invention. In addition, the important role of the identical effect requirement of DOE shall not be ignored.