Invalidity Counter Against Unasserted Claim Does Not Implicate §315(a), PTAB Litigation Blog

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It is well-established that a counterclaim for invalidity in a district court litigation does not trigger the 35 U.S.C. § 315(a) bar. See 35 U.S.C. § 315(a)(3). See also our previous posts here and here discussing strategies for declaratory judgment claims. But what if the patentee asserts fewer than all the claims of the patent-at-issue and the defendant files declaratory judgment counterclaims for invalidity of unasserted claims? Does that trigger the bar? That was the question before a panel of the Board in AMP Plus, Inc. (dba ELCO Lighting) v. DMF, Inc., Case IPR2019-01094. The Board in this case answered the question in the negative.

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