Bottom line: Software patent specifications require disclosure of an algorithm for all means-plus-function limitations. Otherwise, the claim may be invalid for being indefinite. The problem may not be related solely to means limitations since a non-means limitation could be impliedly construed as a means-plus-function limitation even without using the trigger word “means.”
In Eon Corp, IP Holdings LLC v. AT&T Mobility LLC (Fed. Cir. 2015), the patent involved software used in a local subscriber data processing station that operates in tandem with a television to interconnect various interactive features of the television. The patent owner (EON) alleged that the modern iteration of the local subscriber data processing station is a smartphone or cellphone with certain capabilities.
Eon sued 17 defendants for patent infringement. Eon’s patent claims recited 8 means plus function limitations. By statue, means plus function limitations are limited to the structure disclosed in the patent specification and their structural equivalents that perform the recited function. If there is no structure disclosed in the specification for the function associated with the means limitation, then the claim is indefinite and invalid. For softwarepatents, means plus function claims are written with pure functional language. For example, in Eon, one of the means limitations was “means for indicating acknowledging shipment.” Very broad and purely functional. By statute, this limitation is limited to the structure disclosed in the specification and its equivalents that perform the function of “indicating acknowledging shipment.” However, software steps do not have any physical structure. As such, the courts have construed the “structure” of a software step to be the associated algorithm(s) or software program disclosed in the patent specification that performs the recited function.
The Federal Circuit explained that, in general, two types of software means-plus-limitations are litigated: 1) situations where the specification discloses no algorithm and 2) situations where an algorithm is disclosed but the dispute is whether the extent of the algorithmic disclosure is sufficiently definite.
Here, the patent owner agreed that no algorithm was disclosed in the patent specification but argued that the claims were still not indefinite since they fell within the Katz exception. In Katz, the court held that a disclosure of a standard microprocessor can serve as sufficient structure for “functions [that] can be achieved by any general purpose computer without special programming.” Specifically, in Katz, claim terms involving “processing,” “receiving,” and “storing” were not necessarily indefinite because a general purpose computer need not be specifically programmed to perform the recited function.
Eon argued that the various means plus functions limitations which the defendant identified as lacking an associated structure in the specification fit within the Katz exception since they were simple to implement and Eon’s patent disclosed a microprocessor. The Federal Circuit hammered the patent owner on this point since this contention conflates enablement and indefiniteness. Even though a process in software can be easily implemented, the ease of implementation relates to enablement or whether one of ordinary skill in the art can make and use the process. That is a separate requirement for patentability. For a means plus function limitation, a greater burden is placed on the patent owner since the inventor is allowed and has chosen to craft the claim in terms of broad functional language. The inventor must thus describe some structure (i.e., algorithm) associated with the function in the patent specification.
The Katz exception only applies to functions inherent in a standard microprocessor regardless of how easy a non-inherent function might be to implement on a general purpose computer. The court explained that this situation applies only in rare circumstances since any programming required above that which is provided in the general purpose computer would transform the general purpose computer into a special purpose computer.
On one hand, this case is limited in that its holding is applicable only to means plus function claim language. Typically, means plus function limitations are intentionally drafted as a means plus function limitation by using the trigger word “means” and associating a pure function with that “means” term. However, courts may construe claim limitations as a means plus function limitation even though the operative “means” trigger word is not used. Accordingly, to mitigate a finding of indefiniteness and invalidity of a software claim that uses functional language, one should consider drilling down through the functions more carefully and should consider including all available algorithms to perform those functions so that structural support in the patent specification exists even when the claim limitations are construed by the court as a means plus function limitation against the desire of the patent owner.
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