Trusted Knight Corp. v. International Business MacHines Corp.
681 F. App'x 898
| Fed. Cir. | 2017Background
- Trusted Knight owns U.S. Patent No. 8,316,445, which claims software techniques to block key-logging malware (hook-based and form-grabbing) by, e.g., intercepting/clearing form inputs and encrypting keystrokes at low privilege levels.
- Independent claims at issue: claim 1 (and its method counterpart claim 23) and claim 22 (which contains a typographical omission).
- The District Court (D. Del.) held two claim limitations indefinite during claim construction: (1) the phrase “in response to the software key logging through the API stack to an internet communication port” (claims 1 and 23), and (2) the phrase in claim 22 with a missing verb around “hook … inserted.”
- Parties stipulated to a final judgment of invalidity based on those indefiniteness rulings; Trusted Knight appealed.
- The Federal Circuit affirmed, holding that the first limitation fails Nautilus’s reasonable-certainty standard and that the second limitation is not amenable to correction because multiple plausible corrections would alter claim scope.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Whether the claim phrase “in response to the software key logging through the API stack to an internet communication port” is definite | Trusted Knight: phrase means response to the threat of key-logging (whether detected/present or not); specification disclaims dependence on detecting malware | IBM/Trusteer: phrase reads as an event triggered by actual logging; unclear what must occur to trigger the response | Indefinite — phrase does not inform skilled artisans of scope with reasonable certainty (Nautilus standard) |
| Whether the typographical error in claim 22 can be judicially corrected | Trusted Knight: correct by inserting “is” (making it refer to when a hook is inserted) | IBM/Trusteer: correction is debatable; other plausible fixes (e.g., “could be”) would change scope | Indefinite — correction is subject to reasonable debate and claim as written fails Nautilus certainty requirement |
Key Cases Cited
- Nautilus, Inc. v. Biosig Instruments, Inc., 134 S. Ct. 2120 (2014) (patent claims must inform skilled artisans of scope with reasonable certainty)
- Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002) (language limitations and prosecution history contexts for claim scope)
- Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996) (claim construction is a matter of law informing public notice)
- United Carbon Co. v. Binney & Smith Co., 317 U.S. 228 (1942) (warning against zones of uncertainty in claim scope)
- CBT Flint Partners, LLC v. Return Path, Inc., 654 F.3d 1353 (Fed. Cir. 2011) (courts may correct obvious claim errors in certain circumstances)
- Novo Indus. v. Micro Molds Corp., 350 F.3d 1348 (Fed. Cir. 2003) (standards for judicial correction of patent claims)
- I.T.S. Rubber Co. v. Essex Rubber Co., 272 U.S. 429 (1926) (longstanding precedent allowing correction of clerical/obvious errors in patents)