While patent applicants are free to define terms in their patent applications, a recent US Federal Circuit case highlights the risks of using coining terms in patent claims.

AGIS v Life3601 involved a pair of patents related to establishing a communication network for users of mobile devices.2 Each of the claims at issue included the coined term “symbol generator”. The US Federal Circuit held that the claims were invalid because the term “symbol generator” was indefinite.

In the United States, claim elements defined in a functional rather than structural manner may be identified as “means-plus-function” claim elements. Means-plus-function interpretation is usually applied when the term “means” is used in a claim. The absence of “means” language creates a rebuttable presumption that the means-plus-function interpretation should not apply. This presumption can be overcome by showing that a person of ordinary skill in the relevant field would not understand the claim term to have a sufficiently definite meaning as the name for structure.3

“Means-plus-function” claim elements are interpreted narrowly to cover only the specific structures disclosed in the application for accomplishing a function, rather than the function itself. As a result, in order for the claim element to be definite, the specification must include adequate disclosure of structure that performs the function. When a function is computer-implemented, an algorithm for performing that function is usually required unless the function is a basic operation such as processing or storing.4 A more detailed discussion of the disclosure required for means-plus-function claim elements in software patents can be found here.

In AGIS, the term “symbol generator” was interpreted as a “means-plus-function” element because it failed to describe a sufficient structure and merely recited abstract elements for causing actions or performing functions. The Federal Circuit found that “symbol generator” was not used in common parlance by persons of skill in the field to designate structure. Rather, the term “symbol generator” was coined specifically for the patents at issue. The Federal Circuit held that even if the terms “symbol” and “generator” are individually terms of art in computer science, the term “symbol generator” used in the claims suggests an abstraction that describes the function being performed, and does not by itself identify a structure by its function.

Because the term “symbol generator” was interpreted as means-plus-function language, the specification required adequate disclosure of structure that could provide the claimed function. However, the Federal Circuit found that the patents in AGIS did not disclose an operative algorithm for the symbol generator. While the specifications indicated that symbols were generated via a series of databases, this was merely the medium through which the symbols were generated and not an operative algorithm. Accordingly, the Federal Circuit concluded that the specifications did not disclose sufficient structure to provide the symbol generator function.

AGIS highlights the risks of using coined terms in patent claims, particularly for computer-implemented inventions. Specifically, coined terms may be treated as means-plus-function elements and interpreted to cover only the specific corresponding structures disclosed in the specification. Accordingly, if the specification does not provide a clear and complete disclosure of structure that performs the function of the coined term the patent may be invalidated.

While it can be tempting to use coined terms when defining the scope of a claim, it would be prudent to avoid coined terms in the claims of computer-implemented inventions. If coined terms cannot be avoided, patent applicants should be sure to disclose detailed algorithms or processes for performing the claimed function in the specification and/or the figures of a patent application to ensure the claims are not considered indefinite.