Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd.

This case raises the question of whether an equivalent is foreseeable within the meaning of Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, 740 (2001) (“Festo VIII”), and subject to surrender under the doctrine of prosecution history estoppel. We conclude that foreseeability does not require the applicant to be aware that a particular equivalent would satisfy the insubstantial differences test or the function/way/result test with respect to the claim as amended. We hold that Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd. and SMC Pneumatics, Inc.’s (collectively “SMC”) aluminum sleeve was a foreseeable alternative to Festo Corporation’s (“Festo’s”) magnetizable sleeve and that prosecution history estoppel applies. Accordingly, we affirm the district court’s judgment in favor of SMC of lack of infringement of U.S. Patent No. 4,354,125 (filed May 28, 1980) (“’125 patent”). Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., No. 88-1814, slip op. at 2 (D. Mass. June 13, 2005) (“Festo XI”); Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., slip op. 88-1814, p.7 (D. Mass. Jan. 10, 2006) (“Festo XII”) (order denying motion to amend judgment).

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