Using Functional Claim Language in your Patents

1. Kenneth Horton Main: (801) 328-3600
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THE IP LEGAL MINUTE
MARCH 2013: FUNCTIONAL CLAIM LANGUAGE
We should all consider using functional language in claims when possible to keep them broad. But in light of a recent
Federal Circuit decision, I would recommend being very careful about the exact words we use in these functional
limitations. Aspex Eyewear, Inc. v. Marchon Eyewear, Inc., No. 11-1147 (Fed. Cir., Mar. 14, 2012).
The Decision. The claims at issue in this litigation were directed to eyeglasses that contained arms and a pair of magnetic
members “adapted to” extend across sides of the eyeglass frame. The district court had interpreted this phrase narrowly,
requiring that the arms and magnetic members be “made to” extend across the sides of the eyeglass frame. Aspex argued
that this interpretation was too narrow and that the “adapted to” language only required that a structure was “suitable for”
or “capable of” this function.
The Federal Circuit recognized that while the phrase “adapted to” can narrowly mean “made to,” “designed to,” or
“configured to,” it can also be used broadly to mean “capable of” or “suitable for.” Based on two rationales, the Federal
Circuit found that “adapted to” should have the narrower interpretation of “made to.” First, the Court looked to how the
phrase was used in the claim itself and the specification. The Court found that the evidence needed for the broader
interpretation was not present because the specification disclosed that the members and arms were “for engaging,”
suggesting that the members and arms were “made for” such a purpose. Second, the Court relied on the doctrine of claim
differentiation. An adjacent claim 22 recited that first magnetic members were “capable of” engaging second magnetic
members. The fact that the two adjacent claims use different terms in parallel settings supported the conclusion that the
two terms were not meant to have the same meaning and that “adapted to” should be interpreted to have a different
meaning than “capable of.”
The Aspex decision appears to treat functional language like “configured to” as limited to those structures that are
specifically purposed to perform the recited function. But be cautious: this rule has not been adopted by the PTO. See
M.P.E.P. § 2173.05(g). Indeed, a recent Board opinion (Ex Parte Rodriguez) contained reasoning seemingly at odds with
the Aspex decision.
Practice Tips:
1. Aspex stands for the position that “adapted to” can be broader than “configured to” if support can be found in the claims
and the specification. Accordingly, consider using “adapted to” with such a breadth in the specification and the claims.
2. Aspex suggests that “configured to” can be reasonably construed to require a structure that is purposefully made to
achieve the recited function. So amending the claim to recite “configured to” and citing to Aspex during prosecution
might overcome a reference that discloses an element that is not intentionally designed to perform the recited function.
But don’t hold your breath: as we all know, Examiners like to broadly interpret functional language.
3. But beyond the specific language used in Aspex, what other functional language (configured to, adapted to, made to,
suitable to, designed to, etc.) is the broadest? The best way to make sure that your claims contain the broadest functional
language is to draft the claims and specification with this in mind. If you want “ suitable to” to be broader than “designed
to,” make sure “suitable to” is in your independent claim and “designed to” is in a dependent claim. As well, draft your
specification so that this functional language is used consistently: with “suitable” given a broader meaning than
“designed.” If needed, consider using nesting language for all of these terms in the specification and/or claims. For that
matter, considering drafting a form paragraph for your specification which can be included to force the desired
interpretation of functional language.