In litigation, a patentee may assert a device claim that recites an ability of the device to perform a function against an accused device that possesses only the potential to perform the function. The accused infringer may have disabled the function at the factory, or the accused device may perform the function only if a customer modifies the device. Therefore, the accused device’s ability to perform the function may be a latent feature or a latent configuration. In general, whether a device possessing latent functionality will be found to infringe a claim appears to turn on two factors: (1) whether the claim is interpreted to require a capability or a present-ability to perform the recited function; and (2) the degree of modification required so that the device would perform the recited function.
The majority of Federal Circuit decisions to have considered the issue of latent infringement have ruled against the patentee, though there are exceptions. For example, in finding for the patentee, the Federal Circuit in Intel Corporation v. U.S. International Trade Commission held that, because the asserted claim only requires “programmable selection means” and states “whereby when said alternate addressing mode is selected,” the accused device infringed because it could be programmed to perform the infringing use. The accused devices infringed even though they were never sold to operate in the infringing mode and customers were not told how to convert them to operate in that mode. Unstated but implied in the opinion, however, is that it would have been possible for an intended user, without undue modification, to have programmed the devices to operate in the infringing mode.
Similarly, the Federal Circuit found in favor of the patentee in Revolution Eyewear, Inc. v. Aspex Eyewear, Inc., in which the patent claimed an eyeglass device comprising a “primary spectacle frame . . . capable of engaging second magnetic members of an auxiliary spectacle frame.” The Court found that the accused products, “although not specifically designed or sold to be used with top-mounting auxiliary frames, are nevertheless capable of being used in that way. It is irrelevant that Revolution’s auxiliary frames, or any other commercially available auxiliary frames, are not actually used in a top-mounting configuration or cannot be so used.”
Another example of a finding for the patentee at the Federal Circuit is Finjan, Ltd. v. Secure Computing Corp., in which the court affirmed a jury verdict for infringement for program code that was present in the accused device but locked until the customer purchased a key. The accused products in Finjan were downloadable computer security software and hardware containing computer security software. The infringing software modules were locked at the time of sale, “requiring a customer to purchase a separate key to activate each individual module. Therefore, a customer who purchases an accused product can activate all, some, or none of the eight modules at different cost.”
The Federal Circuit in Finjan also affirmed a jury verdict of infringement of system claims reciting “a logical engine for preventing execution,” “a communications engine for obtaining a Downloadable,” and “a linking engine . . . for forming a sandbox package.” The court also affirmed a verdict of infringement of storage-medium claims reciting a “computer-readable storage medium storing program code for causing a server that serves as a gateway to a client to perform the steps of: receiving . . . ; comparing . . . ; and preventing execution . . . .” The court in Finjan explained that “to infringe a claim that recites capability and not actual operation, an accused device ‘need only be capable of operating’ in the described mode. Thus, depending on the claims, ‘an accused device may be found to infringe if it is reasonably capable of satisfying the claim limitations, even though it may also be capable of noninfringing modes of operation.’”
The court based its affirmation of the infringement verdicts on the defendants’ admission that “program code for proactive scanning is ‘literally present’ on all accused products.” According to the court, “it is undisputed that software for performing the claimed functions existed in the products when sold—in the same way that an automobile engine for propulsion exists in a car even when the car is turned off.” By purchasing a key, the user “would be activating means that are already present in the underlying software.”
A year after deciding Finjan, the Federal Circuit addressed similar claim language in Typhoon Touch Technologies, Inc. v. Dell, Inc. The Federal Circuit in Typhoon affirmed a district court’s construction of terms such as “memory for storing” and “processor for executing” as requiring the present-ability to perform the recited functions. The distinction between Typhoon and Finjan appears to be that key-based activation in Finjan activates a functionality already existing in the accused device, whereas in Typhoon there was no evidence that the memory of the accused product is actually programmed or configured to store instructions or data for performing the claimed functions. The court considers activation of an already-loaded software-based functionality an insignificant modification that may not allow the accused device to avoid infringement; such activation is certainly less significant than loading software to a memory as would have been required of the accused device in Typhoon to enable the claimed functions.
A common theme in latent infringement cases is whether a customer would need to modify the accused product for the accused product to perform the steps of the asserted claims. For example, the Revolution Eyewear contrasted capability claims with present-ability claims, such as the asserted claims in High Tech Medical Instrumentation, Inc. v. New Image Industries, Inc., which recited a “camera being rotatably coupled to said body member.” The accused device in High Tech Medical was prevented from rotating only by two screws that could be removed by a user, yet the Federal Circuit found that the accused device was “not rotatable within its housing unless . . . altered.” The Court explained that:
The [district court] read Intel to mean that if a particular device can be altered without undue difficulty to operate in an infringing manner, the device, as sold, must be deemed to infringe. Intel does not support so broad a holding. All that was required by the limitation at issue in Intel was that the claimed invention, an integrated circuit memory device, was “programmable” to operate in a certain manner. The accused device, although not specifically designed or sold to operate in that manner, could be programmed to do so; that is, it was “programmable” to operate in the designated mode. The claim at issue in Intel therefore read on the accused device, as made and sold.
In this way, the Federal Circuit distinguished between the capability claim of Revolution Eyewear and the present-ability claim of High Tech Medical.
Finally, in Nazomi Communications, Inc. v. Nokia Corp., the Federal Circuit construed the asserted claims, which recited modules “to” perform the functions, rather than “programmable to” or “capable of” performing the recited functions, “as claiming an apparatus comprising a combination of hardware and software capable of practicing the claim limitations.” The court in Nazomi found that “the accused devices cannot perform the functionality described in Nazomi’s asserted claims without software.” In other words, the claims are not directed to programmable hardware, but instead to hardware and software capable of performing the function. As a result, the accused devices did “not infringe without modification—the modification of installing the required software,” which the court characterized as “clearly” a modification of the product.
For the patent practitioner, a claiming strategy that includes language such as “a device capable of” performing an operation or “a device for” performing the operation may lead to broader coverage in litigation, as compared to language that merely recites present-ability functionality.
 Bryan Blumenkopf, Exposing Latent Patent Infringement, 19 Rich. J. L. & Tech. 7, 8 (2013).
 Intel Corporation v. U.S. International Trade Commission, 946 F.2d 821, 832 (Fed. Cir. 1991).
 Id. (emphases in original).
 See id.
 Revolution Eyewear, Inc. v. Aspex Eyewear, Inc., 563 F.3d 1358, 1363 (Fed. Cir. 2009).
 Id. (emphasis added).
 Id. at 1370 (emphasis added).
 Finjan, Ltd. v. Secure Computing Corp., 626 F.3d 1197 (Fed. Cir. 2010).
 Id. at 1202.
 Id. at 1205 (emphases in original).
 Id. (quoting Intel Corp. v. U.S. Int’l Trade Comm’n at 832) (internal citations omitted).
 Id. at 1205.
 Typhoon Touch Technologies, Inc. v. Dell, Inc., 659 F.3d 1376 (Fed. Cir. 2011).
 High Tech Medical Instrumentation, Inc. v. New Image Industries, Inc., 49 F.3d 1551 (Fed. Cir. 1995).
 Id. at 1555–56.
 Nazomi Communications, Inc. v. Nokia Corp., 739 F.3d 1339 (Fed. Cir. 2014).
 Id. at 1344 (emphasis added).
 Id. at 1342.
 Id. at 1346.