Federal Circuit Rules IPR Challengers Must Prove Standing Against Substitute Claims Specifically—ironSource v. Digital Turbine

On April 7, 2026, the U.S. Court of Appeals for the Federal Circuit issued a precedential ruling in ironSource Ltd. v. Digital Turbine, Inc., authored by Chief Judge Moore. The court dismissed ironSource’s appeal for lack of Article III standing, holding that a declaration sufficient to establish standing against original claims is not sufficient if it fails to address the specific limitations added in substitute claims approved through a motion to amend at the Patent Trial and Appeal Board (PTAB).

Digital Turbine holds U.S. Patent No. 11,157,256, titled “Instant Installation of Apps,” which claims a network-connected device architecture enabling background downloading and installation of mobile applications without requiring the user to navigate an app store. ironSource, an Israeli software developer, filed an inter partes review (IPR) petition against the patent. PTAB invalidated original claims 1–22 based on the prior art. However, PTAB also granted Digital Turbine’s motion to amend, approving substitute claims 23–37, which added limitations requiring the installation client to check application eligibility and query for network addresses—narrowing the claim scope relative to the original claims.

ironSource sought to appeal the validity of the substitute claims to the Federal Circuit. The court, applying the standard established in JTEKT Corp. v. GKN Automotive, held that an IPR petitioner who appeals approved substitute claims must demonstrate a concrete plan to engage in activity that would be covered by those specific claims. ironSource’s declaration addressed the original claims and the company’s discontinued Aura product, but remained silent as to how the additional limitations in the substitute claims—the eligibility check and network address query—applied to ironSource’s planned or current products. This silence was fatal to standing.

The Federal Circuit’s reasoning reflects the principle that amended claims represent a distinct legal instrument from the original claims. Once PTAB narrows claims through amendment, the amended claims carry their own scope, and a petitioner seeking to challenge that scope on appeal must independently demonstrate infringement exposure under those amended limitations. General references to the parent patent or declarations focused on original claims are insufficient to satisfy Article III requirements when the claims have been substantively narrowed.

The practical implications of this ruling are significant for IPR practitioners. When opposing a patent owner’s motion to amend, petitioners should prepare declarations that explicitly map planned or existing product features to each limitation added in the proposed substitute claims—not merely to the original claims or the underlying technology broadly. Failure to do so risks losing appellate standing entirely if PTAB approves the substitute claims.

This is a precedential decision, meaning it binds future panels of the Federal Circuit. Patent challengers in IPR proceedings who routinely oppose motions to amend will need to rethink their evidentiary preparation, ensuring that standing-related declarations address all claim limitations as proposed—before the amended claims are approved.