US Court Grapples With the Definition of "About"

Earlier this month, the US Court of Appeals for the Federal Circuit dismissed an appeal of a summary judgment decision involving Claim 6 of US Patent No. 5,336,691, owned by Ortho-McNeil Pharmaceutical Inc (Ortho), a claim for a combination of two known pain relievers, tramadol and acetaminophen at a ratio of "about 1:5". A competitor, Caraco Pharmaceutical Laboratories Limited (Caraco), brought a motion for summary judgment of non-infringement on the basis that the Caraco drug had a ratio of 1:8.76 of tramadol to acetaminophen, which it was argued was outside the range of what could be termed "about 1:5". The motion was granted by the District Court and Ortho appealed. The Court of Appeals reviewed the specification and the claims of the patent, and noted that the term "about" meant "approximately" in the context. The Court then addressed the question of how close to 1:5 did a ratio have to be in order to be approximate. The Court held that the proper approach was to consider how the inventor used the term in the patent, and then to consider extrinsic evidence. Some claims of the patent claim a range of ratios, whereas others, such as the claim at issue, Claim 6, claim a specific ratio. The Court reasoned that for the ranges of ratios to mean anything, the use of "about" with a specific ratio must be read narrowly. The Court accepted an expert's evidence that given that the patent discussed the importance of a 95% confidence interval, "about" should be read to accord with that confidence interval. The Court construed "about 1:5" to be a range of ratios from 1:3.6 to 1:7.1. The Court concluded that no literal infringement of the claim had occurred, as Caraco's formulation used a ratio (1:8.76) that was outside the range as construed. The Court also held that the doctrine of equivalents did not apply. During prosecution the applicant had "admitted that it claimed more than it was entitled to claim" by cancelling broader claims, and limiting its application to a specific ratio. The Canadian Federal Court of Appeal considered a similar issue involving the calculation of a ratio in Lubrizol Corp v Imperial Oil Ltd (1992), 45 CPR (3d) 449. In dispute was whether use of a ratio of 1.25 fell within a claim calling for a ratio of "at least 1.3". The Court reasoned that the plain and unambiguous meaning of "at least 1.3" meant that 1.25 did not fall within the language of the claim; however, it further held that it would be unfair to allow a minor or immaterial variant of the invention to escape infringement. In The Lubrizol case, the limit of "at least 1.3" was not considered an essential element of the invention and so the Court found the use of a ratio of 1.25 to infringe. The full text of the Ortho-McNeil decision can be found here: Ortho-McNeil Pharmaceutical Inc v Caraco Pharmaceutical Laboratories Limited, US Court of Appeals Docket # 06-1102 Summary by: James Kosa