While at times commonplace in the patent prosecution world, the U.S. Court of Appeals for the Federal Circuit (CAFC) recently sent a harsh reminder to applicants regarding use of claim language that could be construed as functional.

In Oct. 14’s Bosch, LLC v. Snap-On Inc., the court held that “program recognition device” and “program loading device” were means-plus-function terms requiring the corresponding structure to be described in the specification. This continues a recent CAFC trend to broadly construe certain functional claims terms under 35 U.S.C. §112, ¶ 6. (See Superior Industries v. Masaba where then-CAFC Chief Judge Randall Rader, in a concurring opinion, set forth that “a system claim generally covers what the system is, not what the system does” with reference to commonly used terms such as “configured”)

While functional claim language is permissible, its use generally is employed carefully and in limited situations. This is because adoption of functional language can remove a claim from its broadest reasonable interpretation to limiting claim scope to corresponding structure in the specification directed toward the functional claim language. This is significant at least because it provides competitors’ options to design around and clear avenues to invalidate a patent based on insufficiently described structure.

That is exactly what happened in Bosch, a patent infringement lawsuit where the patentee of U.S. Pat. No. 6,782,313 (the ’313 patent) claimed a diagnostic tester that analyzed whether a control system in a car needed reprogramming. The claimed tester comprised “a program recognition device” and “a program loading device.” Unfortunately, the claim itself lacked any further structural limitations as to either “a program recognition device” and “a program loading device.” This was a problem such that these terms were found to invoke 35 U.S.C. §112, ¶ 6 because the defendant was able to show that no corresponding structure was in fact disclosed.

While conventional terms such as “means for” or “steps for” weren’t used in the claims, the court did discuss whether simple use of the word “means” was enough to invoke §112, ¶ 6 holding that this alone was insufficient to invoke the presumption. However, this can be overcome if it is demonstrated “that the claim term fails to recite sufficiently definite structure or else recites function without reciting sufficient structure for performing that function.”

In fact, there were no figures in the ’313 patent. The patentee argued that plain language of the terms “program recognition device” and “program loading device” sufficiently described physical structures with physical connections to other components that were described in the ’313 patent. While describing how a feature interconnects or interacts with other components is useful, in actuality it was likely dispositive that the specification failed to provide even a single reference to structure for either of “program recognition device” or “program loading device.” Moreover, the patentee was unable to cure these deficiencies through expert statements during trial.

Accordingly, these two terms failed to provide sufficiently definite structure. Further, because no structure was sufficiently provided in the specification, the claims were held invalid.

The lessons here are clear. First, Bosch reinforces the principle that functional claim language should be used with the utmost care. Typically, functional language is recognized in means/steps for claim terms. But with this recent upturn in additional language invoking “means-plus-function” claim construction rules, applicants have no choice but to err on the side of caution and adopt language directed towards structural features versus functional language where possible. Doing so will avoid unfortunate and narrowing §112, ¶ 6 claim constructions later on. If the applicant in Bosch had included even one structural limitation in its independent claim, that may have been enough to avoid §112, ¶ 6 and ultimately a defense of invalidity.

To that end, practitioners must be certain that all claimed structure is sufficiently disclosed in the application at the time of filing. For example, if the applicant here had included just one figure illustrating “a program recognition device” or “program loading device” in some level of detail, §112, ¶ 6 or invalidity could have been avoided. While functional claim language may be necessary to overcome an art reference during prosecution, Bosch is a reminder that the rules of claim drafting are always changing. Unfortunately, one cannot predict whether the terms that may be acceptable today will elicit functional suspicions tomorrow. At a minimum, all known structure related to claim elements should be described in the specification. Providing this level of detail in an application drafting will cure the sting of a particular claim feature being construed as a functional term during enforcement since sufficient structure to correspond to the claimed feature will be available as a fallback (in the event a term is found to invoke §112, ¶ 6).