To be appealable a claim construction order must preclude a finding of infringement—a required element of the plaintiff's cause of action. Princeton Digital Image Corp. v. Office Depot Inc. , 913 F.3d 1342, 1348 (Fed. Cir. 2019). Such preclusion of infringement may be established by the patent owner's binding admission that the accused activities are not infringing under the adopted claim construction.

In both those cases, the issues that the parties sought to appeal did not turn on the merits of the legal claims that they asserted. See Princeton Digital Image Corp. v. Office Depot Inc. , 913 F.3d 1342, 1348 (Fed. Cir. 2019) (noting that Microsoft "establishes that a voluntary dismissal does not constitute a final judgment where the district court’s ruling has not foreclosed the plaintiff’s ability to prove the required elements of the cause of action"). The issue in Microsoft —a ruling on class allegations—"in no way touch[ed] the merits" of the claims.

We have held that "to be appealable[,] a claim construction order must preclude a finding of infringement—a required element of the plaintiff's cause of action." Princeton Dig. Image Corp. v. Office Depot Inc., 913 F.3d 1342, 1348 (Fed. Cir. 2019). We explained that "[s]uch preclusion of infringement may be established by the patent owner's binding admission that the accused activities are not infringing under the adopted claim construction."