On May 6, 2015, the Court of Appeals for the Federal Circuit issued its decision in EON Corp. IP Holdings LLC v. AT&T Mobility LLC, 2014-1393, clarifying that for meeting the definiteness requirement of claims, a general purpose computer can provide sufficient structure for software-implemented means-plus-function claim elements only in very limited circumstances.  As such, the court maintained its well-established rule “that the corresponding structure for a function performed by a software algorithm is the algorithm itself.”  EON Corp. at 7 (citing WMS Gaming, Inc. v. Int’l Game Tech., 184 F.3d 1339, 1348–49 (Fed. Cir. 1999)).  In doing so, the Federal Circuit took a narrow view of its decision from In re Katz Interactive Call Processing Patent Litigation, 639 F.3d 1303, 1316 (Fed. Cir. 2011), which held that a standard microprocessor can serve as sufficient structure for “functions [that] can be achieved by any general purpose computer without special programming.” (emphasis added).  That is, unless a claim limitation in means-plus-function form claims the most basic functions of a computer—such as storing, receiving, or processing data—the specification must disclose an algorithm that implements the function.


EON Corp. IP Holdings LLC (“EON”) asserted U.S. Patent No. 5,663,757 (“’757 patent”) against a number of defendants in Delaware District Court.  The district court granted the defendants’ motion for summary judgment, holding all claims of the ’757 patent invalid as indefinite. In particular, the district court found that the specification failed to disclose an algorithm to provide structure for various computer-implemented means-plus-function elements.  Examples of means-plus-function elements from the ‘757 patent include, (1) “means . . . for indicating acknowledging shipment of an order from a remote station”; and (2) “means for causing selected themes to automatically display a second menu.”  On appeal, the parties agreed that the functions claimed in the terms at issue were all performed by computer software and the Federal Circuit affirmed the district court’s judgment of invalidity.

WMS Gaming and The Katz Exception

Since WMS Gaming, the Federal Circuit has consistently held that the disclosed structure for computer-implemented means-plus-function claims must be more than a general purpose computer or microprocessor.  Accordingly, to avoid indefiniteness under 35 U.S.C. §112, the specification must disclose the corresponding algorithm for a function performed by software.  The court created an exception in Katz when it held that claim terms involving basic “processing,” “receiving,” and “storing” functions were not indefinite because a specially programmed computer was not needed to perform these functions.  In essence, the court in Katz held that, at the most basic level, all computers process, receive, and store data.  Therefore, disclosure of an algorithm for those basic tasks was unnecessary.  In reviewing its only other opinion analyzing the Katzexception, however, the EON court acknowledged that nondisclosure of an algorithm is acceptable only in “rare circumstances.”  EON at 8 (citing Ergo Licensing, LLC v. CareFusion 303, Inc., 673 F.3d 1361, 1364 (Fed. Cir. 2012)).   In Ergo, the court remarked that the function of “‘controlling the adjusting means’ requires more than merely plugging in a general purpose computer.”  Id. at 9 (citing Ergo, 673 F.3d at 1364).

Conclusion: A Narrow Exception

In its EON holding, the Federal Circuit echoed its reasoning from Katz that a microprocessor can serve as structure for a computer-implemented function only where the claimed function is “coextensive” with a microprocessor itself.  EON at 9.  In other words, processing, receiving, and storing data are all functions fundamentally common to all microprocessors, thus making disclosure of an algorithm unnecessary for those functions.  Though EON argued that its claimed functions were “relatively simple to implement,” the court was unconvinced and retorted that “theKatz exception is not so broad” and “‘special programming’ does not denote a level of complexity.”  Id. at 9, 11.  That is, EON’s claimed functions were not fundamental to the operation of a processor but would instead require special programming.  Therefore, the Federal Circuit required disclosure of an algorithm for those functions.

Much like other recent Federal Circuit and Supreme Court opinions, including Alice and Nautilus,EON provides further guidance to patentees that a robust specification should always be a priority.  Specifically, when claiming a software-implemented invention in means-plus-function form, a patentee should not rely on the Katz exception and should almost always disclose at least one algorithm for each means-plus-function limitation.  Even for the basic processing, storing, and receiving functions from Katz, the EON court warned that a narrower construction (i.e., narrower than plain meaning) of those functions may require disclosure of an algorithm.  EON at 11.  The Federal Circuit’s quote from Ergo is instructive here: an algorithm is needed if the function requires more than “merely plugging in a general purpose computer.”