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Foreseeability Does Not Preclude Application of the Doctrine of Equivalents

By Mengyi Wang – Edited by Elise Young Ring & Pinion Service Inc. v. ARB Corporation Ltd., No. 2013-1238 (Fed. Cir. Feb. 19, 2014) Slip Opinion [caption id="attachment_4080" align="alignleft" width="150"] Photo By: Tristan Ferne - CC BY 2.0[/caption] The United States Court of Appeals for the Federal Circuit reversed the United States District Court for the Western District of Washington’s grant of summary judgment, finding that Ring & Pinion Service Inc.’s (“R&P”) Ziplocker product did not infringe ARB Corporation Ltd.’s (“ARB”) U.S. Patent No. 5,591,098 (“the ’098 patent”). Ring & Pinion Service Inc., slip op. at 2. In a unanimous opinion, the Federal Circuit agreed with the lower court that the foreseeability of a cylinder equivalent at the time the patent was filed did not limit the application of the doctrine of equivalents. The doctrine of equivalents accommodates future changes in technology, thus allowing for the continued relevance of a patent despite changes in language or concepts. At issue in this case was whether foreseeability at the time the patent was filed prevented the application of the doctrine of equivalents, and therefore might support a finding a non-infringement. In addition to finding that foreseeability did not limit the doctrine, the court determined that, the district court improperly applied the doctrine of claim vitiation in finding non-infringement. Id. at 8–9. Patently-O summarizes the decision and comments on the underlying policy rationales.The ’098 patent claims an improved automobile locking differential that enables wheels to spin at different speeds relative to each other when unlocked and at the same speed when locked. Id. at 2. R&P sought a declaratory judgment that their product did not infringe ARB’s patent. Id. The parties agreed that R&P’s Ziplocker product literally satisfied all of the limitations of claim 1 of ARB’s patent minus the “cylinder means formed in . . . ” limitation, the equivalent of which was the cylinder in the Ziplocker. Id. at 2, 3. In addition, they agreed that the equivalent cylinder “would have been foreseeable to a person having ordinary skill in the art at the time the application for the ’098 patent was filed.” Id. at 3. However, the parties disagreed over whether the foreseeability of an equivalent at the time of patenting bars the use of doctrine of equivalents and stipulated that the resolution of this single legal issue would conclude the case. Id. On appeal, the Federal Circuit upheld the district court’s ruling that foreseeability does not prevent the application of the doctrine of equivalents; therefore foreseeability would not preclude a finding of infringement under this doctrine. Id. It reasoned that holding otherwise would directly contradict previous cases that ruled that known interchangeability tipped in favor of finding infringement. Id. The Federal Circuit went on to conclude that the district court mistakenly granted summary judgment to R&P. The district court’s error was twofold. First, it should have honored the parties’s stipulation of equivalence. Id. at 8. The court reasoned that the courts are generally bound to enforce a stipulation of fact that has been fairly entered into, and here the parties stipulated to the factual question of equivalence. Id. Second, the district court erred by finding that the vitiation theory trumped the stipulation of fact. The vitiation doctrine (previously covered by the Digest) is an assessment of whether the gap between the accused product and the claim element is too wide to warrant a finding of equivalence; it is not a separate constraint on the doctrine of equivalents, but rather a legal determination on whether a reasonable jury could find equivalence. Id. at 9. Patently-O noted several underlying policy rationales that have animated the extension of the doctrine of equivalents, primarily meant to accommodate after-arising technologies, to foreseeable technologies. For one, patent drafters, tasked with describing an intangible concept, may not have the capability or tool to cover all possible technologies. In addition, since there may be more competitors attempting to design around patents than patent drafters, the doctrine of equivalents serves to level the playing field. On the whole, this case indicates affirmation of the current scope of the doctrine of equivalents by emphasizing that foreseeability does not (and never has) operate as a limitation on the doctrine.