In mechanical and electrical contexts, nearly every single patent application recites a functional limitation in some form. Depending on the context, functional limitations are recited in a plurality of different ways. For instance, applications frequently use “configured to” followed by a desired function. A claim can recite “a housing is configured to rotate about a base.” In other instances, the claim can rely on different language, such as describing the housing as being “rotatable about a base.” Although appearing inconsequential, the difference between reciting a function as an “-able” can change the outcome of an infringement action.

Under the plain meaning, the Federal Circuit interprets “-able” terms and “configured to” as having slightly different scopes. The leading case from the Federal Circuit is Aspex Eyewear, Inc. v. Marchon Eyewear, Inc., 672 F.3d 1335 (Fed. Cir. 2012). Here, the Court analyzed the interpretation of “adapted to” under the plain meaning. In the analysis the Court described two categories of functional language:

• First Category: Being ‘designed to accomplish the specified objective’ (e.g., “configured to,” “designed to”, “made to”); or
• Second Category: Being capable of performing a function (e.g., “capable of,” “suitable for”).

These categories lay the foundation for the cases that follow.

With respect to “-able” terms, such functions are interpreted as being “capable of” under the plain meaning – e.g., in the Second Category. For instance, in Duncan Parking Techs, the Federal Circuit interpreted “receivable within” as “capable of being contained inside.” See Duncan Parking Techs., Inc. v. IPS Grp., Inc., 914 F.3d 1347 (Fed. Cir. 2019). Similarly in Info-Hold, the Federal Circuit interpreted “operable to” under the plain meaning as referring to a “capability” to perform the function. See Info-Hold, Inc. v. Applied Media Techs. Corp., 783 F.3d 1262 (Fed. Cir. 2015).

Being in the Second Category, ‘-able’ may be interpreted as a device that “can be made to serve a specific purpose’, whereas ‘configured to,’ as a term in the First Category, is designed to accomplish the specific objective. Accordingly, phrases with ‘-able’ are have a broader interpretation under the plain meaning.

But plain meaning of claim terms is only the starting point in claim construction, and the entire context of the specification is equally, if not more important.

For example, in Profectus, the Federal Circuit disregarded the plain meaning of an “-able” term in favor of a narrower interpretation based on the specification.  In Profectus, the Court analyzed the claimed feature, “a mountable frame.” The Patentee argued that “mountable frame” should adopt the plain meaning to be interpreted as a frame which is “capable of being mounted.” The Federal Circuit disagreed and interpreted a “mountable frame” as requiring “a feature for mounting”.  The Court relied on the intrinsic evidence, reasoning that the function of ‘mountability’ in the specification corresponded to a specific structural feature such as a hook, clip, or anchor. See Profectus Tech. LLC v. Huawei Techs. Co., 823 F.3d 1375 (Fed. Cir. 2016).

Thus, in Profectus, although the plain meaning of the claim would correspond to the broader Second Category (“-able”), the Federal Circuit essentially applies the same interpretation as “configured to” of the narrower First Category by requiring a specific feature to serve the purpose for mounting. When reciting a mechanical function, the differences between “configured to” and “-able” seem to be negligible. It is unlikely that a mechanical function such as “mountable”, “rotatable”, or the like, could be described without being related to a structural feature – well, such scenario is unlikely without causing other problems under 35 U.S.C. § 112. Thus, reasonably so, Courts appear to disregard the plain meaning of “-able” phrase in the context of mechanical functions.

However, using “capable” or “-able” may be advantageous when referencing a particular objective or intended use. In In re Man Mach., the Federal Circuit interpreted the claimed phrase: “a thumb switch positioned on the top side of the body, the thumb switch being adapted for activation by a human thumb.” The issue was whether “adapted for” would be interpreted as “capable of” (e.g., the thumb switch can be activated by any finger) or “configured to” (e.g., the thumb switch requires activation through a human thumb). The Federal Circuit narrowly interpreted the thumb switch as being “configured to,” i.e., as “being made or designed for activation by a human thumb.” See In re Man Mach. Interface Techs. LLC, 822 F.3d 1282.

In contrast, if the claim had recited “a thumb switch capable of being activated by a human thumb,” then the Court could have more broadly interpreted the thumb switch as capable of be activated by any finger.  But, as in Profectus, the Court referred to the specification and interpreted the claims in light of how the invention was described.

Especially in the context of the “thumb switch” of In re Man Mach., the difference between “capable of” and “configured to” resembles an inquiry into the objective intent. Did the specification indicate that the thumb switch was objectively configured for activation by a human thumb, or broadly indicate that activation by a thumb was merely a possibility?  In In re Man Mach, the Federal Circuit evaluated the totality of the evidence to determine how the switch was specifically designed to be used. In every application, this analysis is not inconsequential.

In an unpublished/non-precedential opinion, the Federal Circuit analyzed a claim in which the differences between “capable of” and “configured to” likely changed the outcome of an infringement action. In Corus Realty Holdings, the Court was faced with interpreting “a cellular-based data receiver configured to obtain cellular-based location data.” Zillow, the Defendant alleged to infringe Corus, produced an application to be implemented on a smart phone, such as an IPhone or Android. In the allegedly infringing application, Zillow would acquire location data from the local operating system. In this case, the location data is not limited to cellular-based data, but rather could be sourced from the Wi-fi, Bluetooth, or any combination thereof.

In finding non-infringement, the Federal Circuit said that a device being “reasonably capable of being put into the claimed configuration is insufficient for a finding of infringement," where the claim “specified a particular configuration.” The Court emphasized how Zillow’s application does not itself determine a user’s location but requests the information from the local operating system.

It is worth noting that many other inquiries likely swayed the outcome of this particular case. The Federal Circuit emphasized how, during prosecution, the claim was changed from “a cellular-based data receiver capable of obtaining location data” to “a cellular-based data receiver configured to obtain cellular-based location data.” Thus, the Federal Circuit did not find a reason to overturn the District Court’s narrow interpretation. In similar circumstances with different intrinsic evidence involved, perhaps a different conclusion would be reached. But this is merely an example of how “configured to” and “capable of” can change a win to a loss – or vice versa.

If the Federal Circuit has iterated any principal from these decisions, it’s how information from the specification can be more persuasive than the plain meaning in the context of “-able” and “configured to”. As described above, in some contexts such as when reciting an intended use, “-able” may be advantageous. By contrast, in other contexts, the difference in interpretation may be inconsequential. However, in every context, these decisions stress the importance of drafting a specification in a non-limiting manner and avoiding estoppel during the prosecution process.