TAKEAWAY: Federal Circuit provides guidance on “reasonable certainty” of claimed relative terms.

In Exmark MFG. Co. v. Briggs & Stratton Power Prods. Grp., LLC, the Federal Circuit addressed whether a claimed baffle portion of a lawn mower that was “elongated and substantially straight” was definite under § 112. Briggs & Stratton argued that the ’863 patent does not explain how to objectively determine whether a baffle portion is straight enough or long enough to be “elongated and substantially straight” for purposes of determining infringement. The Federal Circuit held that the claim language and specification of the ’863 patent provide reasonable certainty as to the meaning of “elongated and substantially straight.”

In particular, the Federal Circuit looked to the disclosed structure of the “elongated and substantially straight” baffle portion in relation to other disclosed structures, and in light of the disclosed function of the baffle portion, to find certainty in the claim terms. For example, the Federal Circuit found the “substantially straight” portion to be straight relative to curved baffle portions disclosed in the patent. Further, the court found the claimed function of the baffle portion (to deflect cuttings toward a second blade) provided further guidance regarding how elongated and straight the baffle portion needed to be.

The court’s decision shows that sufficiently describing features in the specification and drawings can help provide certainty to relative terms in your claims.