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Justin E. Gray

Partner at Eversheds Sutherland (US) LLP

Former Adjunct Professor at Northwestern University School of Law

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Federal Circuit Prefers Construction that Harmonizes Claim Elements to Define a Workable Invention

Lexion Medical, Inc. v. Northgate Technologies, Inc. (Fed. Cir. Apr. 22, 2011)

In this case, the Federal Circuit affirmed the district court's claim construction as it harmonized the elements of the claim to define a workable invention.  The patent at issue related to an apparatus for heating and humidifying gas to a predetermined and preset temperature for use during laparoscopic procedures.

One limitation of the patent claims at issues required gas to enter the patient "humidified and having a temperature within 2°C of the predetermined temperature."  The district court held that this limitation did not require that the temperature range always be within 2°C of the predetermined temperature because the patent specification disclosed that that temperatures "will, at times, fluctuate outside the four-degree range."  The defendant argued that the claim construction of this limitation should require that the temperature always be within 2°C of the predetermined temperature.

The Federal Circuit agreed with the district court, mainly relying on the specification and surrounding claim language.  More specifically, two other limitations of the claim required "sensing the temperature of the gas as it exits the chamber to determine if it is in the predetermined range" and "actuating the heating means if the temperature of the gas is without the predetermined range."  The Federal Circuit found that these limitations, along with similar disclosure in the patent specification, supported a construction allowing for minor fluctuations outside the 4°C range, and stated that the Court "prefers a claim interpretation that harmonizes the various elements of the claim to define a workable invention."