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Justin E. Gray

IP Litigation Attorney at Foley & Lardner LLP

Former Adjunct Professor at Northwestern University School of Law

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Properly Construed Claims Failed to Read on Preferred Embodiment and Were Found Indefinite

Purechoice, Inc. v. Honeywell Int'l, Inc. (Fed. Cir. Jun. 1, 2009)

In this case, the district court (Eastern District of Texas) found several claims of the patent at issue invalid under the definiteness requirement of 35 U.S.C. 112. The Federal Circuit, in a per curiam opinion, affirmed.

The patent at issue related to a system and method for acquiring and monitoring certain types of air and water quality data, including a set of sensors and data storage devices couple to the sensors. At issue was construction of the claim element "air quality." Purechoice argued that the term should be construed simply as "the quality of the air." Honeywell argued for a narrower meaning based on the claims, specification, and prosecution history: "the concentration of pollutants or contaminants in the air," excluding "meteorological, climate, or comfort related variables, such as temperature and humidity." The district court held that "air quality" means the "concentration of pollutants or contamina[nts] in the air." The court then agreed with Honeywell that two phrases including the term "air quality" were impossible to construe and differentiate from one another: "sensor for measuring environmental air quality data" and "air quality sensor adapted to measure non-weather data."

The Federal Circuit found that PureChoice's construction of "air quality" "does not inform the public what qualities the invention is concerned with, and is overbroad.". While the Court was "[m]indful not impute an attribute of a preferred embodiment into a claim term" the Court recognized that "preferred embodiments nevertheless are evidence of [the term's] meaning." The preferred embodiment for the patent at issue did not disclose meteorological sensing, but rather employed an organic compound sensor. Further, the specification clearly showed "that the invention is concerned with contaminants and pollutants, and not meteorological attributes."

Relying on the specification, the Court found that the "claimed invention is narrower than the claim language might imply, making it proper to limit the claims." The prosecution history supported this outcome as well, as the inventors amended the claims to get around prior art that disclosed measuring meteorological attributes. The Federal Circuit found this to show PureChoice had "clearly and unmistakably disavowed environmental data insofar as it extends beyond contaminants and particles."

Turning to indefiniteness, the Court determined that once the proper construction of "air quality" was applied to the claim terms "sensor for measuring environmental air quality data" and "air quality sensor adapted to measure non-weather data," the two terms became "identical in meaning" but also "insolubly ambiguous." Father, the claims as construed could not be read on the preferred embodiment. Finally, the Court noted that PureChoice had not reduced the interviews that resulted in its amended claims to writing pursuant to 37 C.F.R. 1.560(b) and therefore the Court was left without a record to explain the difference in meaning between the two terms. For these reasons, the Federal Circuit found the claims to be indefinite and therefore invalid.

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