Ibormeith IP, LLC v. Mercedes-Benz USA, LLC, 732 F.3d 1376 (Fed. Cir. 2013).

Patentees generally desire to obtain the largest scope of protection possible for their inventions. To aid with this desire, 35 U.S.C. § 112(f) allows use of means-plus-function claims to protect an invention against structural equivalents. But when using these claims, patentees must ensure that the specification renders the bounds of the claim by adequately defining a structure. Without an adequate structural description, a court will invalidate the means-plus-function claim because it is indefinite. Recently, in Ibormeith IP v. Mercedes-Benz, the US Court of Appeals for the Federal Circuit concluded that “a description of an algorithm that places no limitations on how values are calculated, combined or weighted is insufficient to make the bounds of the claim understandable.”

In this case, Ibormeith alleged that Mercedes infringed claims 1, 5, 8, and 9 of U.S. Patent No. 6,313,749, entitled “Sleepiness Detection for Vehicle Driver or Machine Operator.” Mercedes argued that the means-plus-function limitations in independent claims 1 and 9 were indefinite. Both parties agreed with the district court that a motion for summary judgment, concerning whether the independent claims were indefinite, should be pursued as a threshold issue. On September 5, 2012, the district court found the independent claims indefinite and granted Mercedes’ motion for summary judgment. Just over a year later, on Oct. 22, 2013, the Federal Circuit affirmed the district court’s decision because one could not understand the bounds of these claims.

On review, the Federal Circuit first looked at the independent means-plus-function claims. Claim 1 claimed “computational means for weighting the operational model, . . . deriving, from the weighted model,” the amount of driver sleepiness, and “producing an output determined thereby.” Similarly, Claim 9 claimed “computational means for computing steering transitions and weighing that computation . . . to provide a warning indication of driver sleepiness.” Thus, to support this claim, the specification needed to describe a structure for “computational means.”

So the court searched the specification for a structure that would provide boundaries for “computational means.” The court focused on Table 10, entitled Sleep Propensity Algorithm—Definition. Table 10 provided a mathematical equation that added eight “algorithm elementals” to determine sleep propensity.

In interpreting Table 10, the court relied heavily on the opinion given by Ibormeith’s expert, Dr. Jochem. Despite the fact that Table 10 added all of the algorithm elementals together, according to Dr. Jochem, the disclosed computational means is an “algorithm template” that need only use certain algorithm elementals listed in Table 10, and may select from the others. Also, Dr. Jochem testified that instead of addition, the weighting of the algorithm elementals “could be performed by multiplication or a function that has some linear or nonlinear terms.” Thus, according to the court, Ibormeith’s own expert asserted that this “algorithm template” would require “one who implements the drowsiness detection system to determine which factors to use in the algorithm, how to obtain them, how to weight them, and when to issue a warning.”

After hearing Dr. Jochem’s testimony, the court treated it as a binding admission, which led to invalidity of the claims. Indeed, because of this admission, the court refused to decide whether the equation listed in Table 10 could provide a definite algorithm. Instead, the court interpreted Table 10 to cover “all ways of taking into account the listed variables, or some subset of the variables, that a skilled artisan would find appropriate.” Under this reading, Table 10 failed to provide a defined understandable algorithm. Therefore, because the independent claims were indefinite, the Federal Circuit affirmed the district court’s grant of summary judgment.

In this case, it is clear that Ibormeith mistakenly attempted to broaden the means-plus-function claim by broadening Table 10’s interpretation. Instead, Ibormeith should have focused on describing a “straightforward,” “concrete” algorithm structure, for which structural equivalents could be determined. In its opinion, the Ibormeith court referred to two examples of a straightforward algorithm structure. In the first, Typhoon Touch Technologies v. Dell, the Federal Circuit upheld a claimed “means for cross referencing” because the specification stated that “cross-referencing entails the steps of data entry, then storage of data in memory, then the search in a library of responses, then the determination if a match exists, and then reporting action if a match is found.”1 In the second, WMS Gaming v. International Game Technology, the Federal Circuit found that “means for assigning a plurality of numbers” was sufficiently disclosed because a figure in the patent depicted the relationship of a virtual reel with a physical reel2.

In reliance on these examples, to support a means-plus-function claim, the specification should describe a specific structural algorithm by explaining the steps to perform the function or by depicting a concrete working model that performs the function. As further support, an expert should aid by explaining precisely how the specific steps perform the function or how the disclosed model performs the function.



1. Typhoon Touch Techs., Inc. v. Dell, Inc., 659 F.3d 1376, 1386 (Fed. Cir. 2011).
2. WMS Gaming Inc. v. Intl. Game Tech., 184 F.3d 1339, 1349 (Fed. Cir. 1999).