This case involves patents for rapid-hardening, high-strength cement. A few of the issues are discussed below.
The Federal Circuit reversed the district court’s claim construction of “soluble CaSO4 anhydride” in part because it relied too heavily on a single dictionary definition divorced from the context of the claims and the specification. “[T]he [district] court erroneously relied on expert testimony and a single dictionary definition to the exclusion of other dictionary definitions and, most importantly, the context in which the term was used within the claim and the specification.” (p. 9.) The issue was whether “soluble CaSO4 anhydride” meant “a compound formed from an acid by removal of water” as the district court held or meant “soluble anhydrous calcium sulfate.” Because there was ambiguity in the dictionary definitions regarding what anhydride could mean, “the context must define what compound has had water removed. Here it is calcium sulfate, not an acid.” (p. 10.)
“An infringer does not escape liability merely by infringing in secret.” (p. 15.) Therefore, summary judgment of laches was not appropriate even though the accused product was available for 12 years because the patentee could not adequately test it until discovery. While 12 years is a long time, when “a claim limitation whose presence is undetectable in a finished product, it is reasonable that [patentee] might not have known or been able to find out whether [a product] infringed.” (p. 15.) Thus, there were genuine issues of fact, including whether the patentee had fulfilled its duty by hiring a private investigator.
“Merely claiming broadly does not render a claim insolubly ambiguous, nor does it prevent the public from understanding the scope of the patent.” (p. 19.) Thus, the fact that one formula in the claims may have covered 5000 variations did not render them indefinite because a person could fairly easily determine whether a given compound fell within the literal scope of the claims.
Correction of Typo
The district court refused to correct a typo (insertion of a comma) because, although the error was apparent to one of skill in the art, it was not “clear on the face of the patent.” The Federal Circuit clarified that such corrections can be made “if the correction is not subject to reasonable debate to one of ordinary skill in the art, namely, through claim language and the specification, and the prosecution history does not suggest a different interpretation, then a court can correct an obvious typographical error.” (p. 21.)