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Recent Case Regarding Successful Patent Non-Infringement Defense Based on Practicing Prior Art
"'Practicing prior art' defense" is a type of argument employed in defense of alleged patent infringement. If a product accused of infringement embodies technology the same as (or highly similar to) the prior art, it cannot be considered to constitute patent infringement, since prior art technology can in no way infringe on a patent filed subsequently. However, in practice, this defense is rarely used, and court judgments on the same are, accordingly, relatively rare.
Recently, the Intellectual Property and Commercial Court issued a first-instance judgment (Judgment No. 111-Civil-Patent-Suit-58 issued on February 21, 2023), determining that the "practicing prior art defense" applies to this case, and therefore the accused product does not constitute infringement. The case was appealed, and the same court issued a second-instance judgment (Judgment No. 112-Civil-Patent-Appeal-8 issued on January 18, 2024), upholding the conclusion of the first-instance judgment. The following is a brief summary of the case.
I. Both parties' arguments
- The plaintiff argued that the accused product was found to fall within the scope of Claims 1 and 2 of Taiwan Patent No. M581023 (hereinafter the asserted patent), and infringe on the plaintiff's patent rights. The claims of the asserted patent recite the following.
l Claim 1: A top push structure of a clamping mechanism, comprising a worktable with a clamping rod on the bottom surface, the clamping rod correspondingly embedded in a clamp head which has a piston seat with a central through-hole and a base body sealing the through-hole, a movable seat with a central hole for the clamping rod to be inserted, and a clamping device surrounding the movable seat to secure the clamping rod, and several elastic members around the piston seat, allowing the piston seat to rise and fall to release or clamp the clamping rod of the worktable, characterized in that a through hole at the central area of the bottom of the movable seat, and a protrusion corresponding to the through hole on the base body for pushing against the clamping rod.
l Claim 2: A top push structure of a clamping mechanism as described in claim 1, where the piston seat and the base body are integrally formed.)
- The defendant submitted two prior art references, namely Exhibit 1 (TW385265) and Exhibit 2 (a video "Stark SPEEDY Classic Zero Point Clamps by Roemheld" publicly available on YouTube on October 12, 104), and argued as follows.
(1) All technical features related to the accused product and the asserted patent are the same as the technology recited in either Exhibit 1 or Exhibit 2, so the "practicing prior art" defense should be applied rather than the Doctrine of Equivalents. Thus the accused product has not committed equivalent infringement.
(2) While not disclosed in Exhibit 1 or Exhibit 2, some technical features of Claims 1 and 2 of the asserted patent are realized by substantially the same technical means and produce substantially the same results as Exhibits 1 and 2, verifying that claims 1 and 2 of the asserted patent can be easily completed by a person skilled in the art based on the prior art and thus lack inventiveness.
II. Court Judgement
1. The first and second instance courts expressed differing interpretations of "活動座" (movable seat) recited in the asserted patent claims. The first instance court adopted the plaintiff's interpretation, i.e., "a seat that allows the engaging holder to move," while the second instance court interpreted it as "a seat that can move up and down."
2. The court compared the accused product with Exhibit 1 and Exhibit 2 (parts of the drawing and photos provided in the first instance judgment are as follows).
- The court pointed out that the technical features of the accused product that fall within the scope of Claim 1 of the asserted patent are a top push structure of a clamping mechanism, a worktable with a clamping rod on the bottom surface correspondingly embedded in a clamp head, a piston seat with a central concave hole, and a movable seat with a central hole into which the clamping rod is inserted. The accused product also has features within the scope of Claim 2, specifically the piston seat having a bottom with a closed end and the same thickness. However, these technical features are the same as a single prior art technology (Exhibit 1 or Exhibit 2), so the "practicing prior art" defense applies.
- "'Practicing prior art' defense" means that the scope of a patent cannot be expanded to cover the same scope as a single prior art or a technology that can be easily completed based on a single prior art. When determining whether the Doctrine of Equivalents applies, if the accused infringer's defense is based on "practicing prior art" and it is found that all technical features within the scope of the patent are the same as a single prior art or the single prior art combined with utilization of known technique, the "practicing prior art defense," applies over "Doctrine of Equivalents", and the alleged infringing object cannot be found to have committed equivalent infringement.
In Taiwan, using "practicing prior art defense" to assert non-infringement is relatively rare, possibly due to being considered a defense for excluding application of the Doctrine of Equivalents. The accused infringer may be concerned that "'practicing prior art' defense" is a kind of explicit or implicit indication that the accused product falls within the equivalent scope of the asserted patent. Therefore, the accused infringer often argues that the patent lacks inventiveness and should be revoked based on prior art similar to the accused product. However, the defense of non-infringement based on practicing prior art is still recognized by the local courts in practice, especially when judges wish to prioritize determination of infringement and avoid directly concluding invalidity of the asserted patent which the patentee put a lot of effort to obtain.
In the present case, the first instance judgment recorded that the two parties did not dispute that "the accused product falls within the equivalent scopes of Claims 1 and 2 of the asserted patent2," but the defendant argued that the "'practicing prior art' defense" should be applied to this case so infringement assertion based on "Doctrine of Equivalents" should not be recognized. Ultimately, the court provided no analysis of differences between the prior art exhibits (i.e., Exhibit 1 and Exhibit 2) and Claims 1 and 2 of the patent to determine whether the claims are inventive. The court compared only the accused product with Exhibits 1 and 2 separately, and determined that the technical features of the accused product falling within the scope of Claims 1 and 2 were the same as in a single prior art, therefore not constituting equivalent infringement.