Centripetal Networks v. Keysight Technologies — Federal Circuit Expands Obviousness to All Cybersecurity Patent Claims

Background

U.S. Patent No. 10,193,917, titled “Rule-Based Network-Threat Detection,” covers a packet-filtering device that receives network packets, applies security rules to determine whether to block or allow each packet, generates detailed log entries (including threat identifiers), and updates a “packet flow entry” that consolidates multiple log entries corresponding to a common threat — ultimately presenting the data on a network defender’s dashboard. Centripetal Networks asserts this patent covers its CleanINTERNET cybersecurity platform and is infringed by Keysight Technologies’ Vision product line.

In 2022, Keysight filed a petition for inter partes review (IPR) — a USPTO Patent Trial and Appeal Board (PTAB) proceeding allowing accused infringers to challenge a patent’s validity. The PTAB found most claims of the ‘917 patent (claims 1–3, 5–13, and 15–20) unpatentable as obvious over prior art: the Sourcefire 3D security system’s user guide combined with the Macaulay cyber threat intelligence patent application. However, the PTAB found claims 4 and 14 not obvious, construing the term “responsive to” in those claims to require continuous real-time updating — a feature it found the prior art did not teach.

The Court’s Holding

The Federal Circuit affirmed the PTAB’s obviousness findings for claims 1–3, 5–13, and 15–20, agreeing that Sourcefire (a real-time network defense system with intrusion event logging and flow analysis dashboards) combined with Macaulay’s cyber threat intelligence framework taught all elements of those claims. The Board’s claim construction of “packet flow entry” — as a consolidated data structure for multiple log entries corresponding to a common threat identifier — was correct and supported by the claim language itself.

On cross-appeal by Keysight, however, the court reversed the PTAB’s non-obviousness finding for claims 4 and 14. Those claims used the phrase “responsive to” — and the Board had construed this to require continuous updating of a packet flow entry. The Federal Circuit found that construction wrong: “responsive to” in the claim language simply means triggered by an event, not necessarily requiring continuous or real-time operation. Under the correct construction, Sourcefire also rendered claims 4 and 14 obvious. All 20 claims of the ‘917 patent are now unpatentable, which simultaneously mooted the ‘917 patent issues in the companion ITC case (No. 24-1416, also decided April 23, 2026).

Key Takeaways

• The Federal Circuit reversed the PTAB’s non-obviousness finding for two claims solely on claim construction grounds — how a key term is interpreted often determines the entire obviousness analysis.
• “Responsive to” in patent claims means triggered by an event; it does not inherently require continuous or real-time operation — patent drafters should use explicit language if continuous updating is a critical limitation.
• When a patent is declared unpatentable in an IPR, companion ITC proceedings asserting the same patent become moot — IPR and ITC strategies must be coordinated from the outset.
• All 20 claims of U.S. Patent No. 10,193,917 are now unpatentable, significantly weakening Centripetal’s IP position in its broader dispute with Keysight.

Why It Matters

This case illustrates how an IPR can be a more efficient and decisive weapon than district court litigation for accused infringers. By challenging the ‘917 patent through the PTAB simultaneously with defending at the ITC, Keysight eliminated the patent entirely — and mooted the ITC proceedings in one stroke. For companies in cybersecurity and other technology sectors where products are built on prior-art systems like established intrusion detection platforms, the IPR-plus-ITC defense combination can be highly effective. Practitioners should also note the claim construction lesson: terms that seem to imply continuous operation (“responsive to”) may be construed more narrowly than expected, and precise drafting is essential to preserve the intended scope.