The Federal Circuit recently addressed the definiteness of means-plus-function limitations in a case involving sleepinessmonitoring technology. Affirming a grant of summary judgment of indefiniteness, the court bound plaintiff Ibormeith IP, LLC ("Ibormeith") to its expert's broad infringement assertions, and held that providing a "template" for a person of ordinary skill in the art to construct an algorithm may be insufficient to define a structure under 35 U.S.C. § 112(f). Ibormeith IP, LLC v. Mercedes-Benz USA, LLC, 732 F.3d 1376 (Fed. Cir. 2013).
Section 112(f) permits a claim limitation to be "expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof." Such "means-plus-function" limitations are "construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof." Id. In return for this benefit of including equivalents in the literal coverage of a claim, the patentee must sufficiently define in the specification a structure tied to the claim. Ibormeith IP, 732 F.3d at 1379.
The Ibormeith case involved U.S. Patent No. 6,313,749 ("the '749 patent"), titled "Sleepiness Detection for Vehicle Driver or Machine Operator." The '749 patent addresses monitoring a vehicle driver's sleepiness by taking into account multiple factors, including circadian rhythm, repeated or large corrective steering actions, monotony of road, cabin temperature and length of driving session.
Ibormeith brought suit against Mercedes-Benz USA, LLC ("Mercedes-Benz"), and Daimler AG ("Daimler"), asserting two independent claims subject to the requirements of 35 U.S.C. § 112(f) and two claims depending from those independent claims. Ibormeith IP, LLC v. Mercedes-Benz USA, LLC, 889 F. Supp. 2d 677, 680 (D.N.J. 2012). One independent claim included the limitation "computational means for weighting the operational model according to time of day in relation to the driver or operator circadian rhythm pattern(s) and for deriving, from the weighted model, driver or operator sleepiness condition and producing an output determined thereby." Id. at 681. The other included a similar limitation: "computational means for computing steering transitions and weighing that computation according to time of day, to provide a warning indication of driver sleepiness." Id.
Ibormeith argued that the corresponding structure was an algorithm in the specification's text or tables (Table 10). Id. at 685. Ibormeith cited text that included "a monitor taking account of circadian and sleep parameter . . . integrated with 'real-time' behavioral sensing," and an explanation that aberrant steering behavior "could be recognized and corrected." Id. at 685-86. Table 10 presented an equation under the title "Sleep Propensity Algorithm – Definition": S mod = S circ + S zerox + S rms + S light + S temp + S sleep + S road + S trip. Id. at 686.
The district court rejected these arguments. It held that the cited text simply described the claimed function and that Table 10 did not disclose an algorithm for deriving a score for driver sleepiness or for providing a warning indication of sleepiness. Id. at 685-86, 692.
The Federal Circuit agreed. The court stated that the only substantial question was whether an algorithm was found in Table 10, and therefore focused its discussion on the table. Ibormeith, 732 F.3d at 1379.
The Federal Circuit relied heavily on Ibormeith's litigation positions to reach the conclusion that Table 10 did not provide the necessary algorithm. The court noted that Ibormeith's expert opined that Table 10 was not meant to be an algorithm that simply added inputs, but rather an algorithm "template." Id. at 1381. According to Ibormeith's expert, the patent allows the implementer of a drowsiness-detection system to determine "which factors to use in the algorithm, how to obtain them, how to weight them . . . how to combine them, and when to issue the warning." Id. The expert interpreted the patent to provide this broad corresponding structure in order to encompass the accused products. Id.
The court treated this broad reading of the corresponding structure as a "binding admission" that rendered the limitation indefinite. Id. Ibormeith's position suggested that Table 10 covers all ways of taking into account the variables that a person of ordinary skill in the art would find appropriate. Id. In the view of the court, this broad reading left the disclosure "without an algorithm whose terms are defined and understandable." Id. The Ibormeith case illustrates the importance of both providing adequate corresponding structure in the specification for a Section 112(f) limitation, and avoiding reading that structure so broadly as to render the limitation indefinite.
Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.
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