Means-Plus-Function Software Claims Indefinite Where Corresponding Algorithm Not Disclosed: Federal Circuit | Practical Law

Means-Plus-Function Software Claims Indefinite Where Corresponding Algorithm Not Disclosed: Federal Circuit | Practical Law

In EON Corp. IP Holdings LLC v. AT&T Mobility LLC, the US Court of Appeals for the Federal Circuit held that the patent specification must disclose an algorithm as the corresponding structure for computer-implemented means-plus-function claim elements, except where a general purpose computer or microprocessor is coextensive with the claimed function.

Means-Plus-Function Software Claims Indefinite Where Corresponding Algorithm Not Disclosed: Federal Circuit

by Practical Law Intellectual Property & Technology
Published on 07 May 2015 • USA (National/Federal)
In EON Corp. IP Holdings LLC v. AT&T Mobility LLC, the US Court of Appeals for the Federal Circuit held that the patent specification must disclose an algorithm as the corresponding structure for computer-implemented means-plus-function claim elements, except where a general purpose computer or microprocessor is coextensive with the claimed function.
On May 6, 2015, in Eon Corp. IP Holdings LLC v. AT&T Mobility LLC, the US Court of Appeals for the Federal Circuit affirmed the US District Court for the District of Delaware's summary judgment that all of the patent owner's means-plus-function software claims were invalid as indefinite under former 35 USC § 112 ¶ 6 because the patent specification did not disclose algorithms as the corresponding structure (No. 2014-1392, (Fed. Cir. May 6, 2015)).
EON Corp. IP Holdings LLC asserted US Patent No. 5,663,757 (the '757 patent), a software patent, against 17 accused infringers, including smartphone manufacturers, cellular network providers and smartphone content providers (collectively Accused Infringers). The Accused Infringers moved for summary judgment of invalidity for indefiniteness, which the district court granted.
All of the '757 patent's claims included computer-implemented means-plus-function limitations but the '757 patent:
  • Only disclosed a microprocessor as the corresponding structure.
  • Did not disclose any algorithm for performing the relevant functions.
The Federal Circuit explained that, generally, the corresponding structure for functions performed by a software algorithm is the algorithm itself. However, the court noted the rare exception, described in In re Katz Interactive Call Processing Patent Litigation, where a general purpose computer or microprocessor can serve as structure for a computer-implemented function if the claimed function is coextensive with the computer or microprocessor (639 F.3d 1303 (Fed. Cir. 2011)).
EON argued that the functions claimed in the '757 patent fell within the Katz exception because they were relatively simple to implement and did not involve special programming. The Federal Circuit rejected this argument, explaining that:
  • The special programming exception in Katz does not denote a level of complexity.
  • A microprocessor can serve as corresponding structure in this context only for the microprocessor's basic functions.
The Federal Circuit also rejected EON's argument that a microprocessor can serve as sufficient structure for a software function if a person of ordinary skill in the art could implement the software function because this argument confused the definiteness requirement of Section 112 Paragraphs 2 and 6 with the enablement requirement of Section 112 Paragraph 1. Specifically, enablement requires determining whether a person of ordinary skill in the art could devise some means of carrying out the claimed function. In contrast, the question here is whether the specification discloses corresponding structure to satisfy Section 112, paragraph 6.
Based on the foregoing, the Federal Circuit affirmed the district court's grant of summary judgment of invalidity.