Federal Circuit: An Expired Patent Can Still Be Cancelled in IPR (BT Americas v. Palo Alto Networks)
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On 29 October 2026, the US Court of Appeals for the Federal Circuit affirmed a Patent Trial and Appeal Board (PTAB) decision that all 25 challenged claims of a network intrusion monitoring patent are unpatentable as obvious. The nonprecedential opinion in BT Americas, Inc. v. Palo Alto Networks, Inc. (No. 2025-1572) is short, but it restates a point that matters to anyone holding old patents: expiry does not put a patent beyond the reach of inter partes review (IPR).
The patent and the challenge
US Patent No. 7,895,641 describes a system for dynamic network intrusion monitoring, detection and response. Probes collect data inside a customer's network, filter it and pass on noteworthy events, and the system can modify the probe's analysis capability during operation. The PTAB found claims 1 to 25 unpatentable under 35 U.S.C. § 103 in IPR2023-00889, and BT Americas appealed.
Obviousness upheld
The panel (Judges Chen, Stoll and Stark, opinion by Judge Chen) held that substantial evidence supported the PTAB's findings. The prior art, a filtering system that allowed its database to be edited online, already modified the probe's analysis capability as soon as the database changed. The court also accepted that dynamic modification was a common database feature at the time, and it upheld the motivation to combine the two references.
The expired patent point
On appeal, BT Americas also argued that the PTAB had no jurisdiction because the patent had expired before the petition was filed, so it no longer involved any public right. The court rejected this, pointing to its earlier precedential decision in Apple Inc. v. Gesture Technology Partners (2025), which held that the argument is incompatible with the Supreme Court's reasoning in Oil States (2018). The panel said it was bound by that precedent and saw no persuasive reason to depart from it anyway.
Why it matters
Owners of expired patents often still assert them for past damages, up to six years back under US law. This decision confirms that the IPR route stays open to accused infringers in that situation. For patent owners, a licensing or litigation campaign built on an expired patent should be planned on the basis that the PTAB can still be asked to cancel it.
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