Broad Construction of Claimed Numerical Range Affirmed
Lexion Medical v. Northgate (decided 4/22/11)By: Karen V. Martin
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What This Means to You
- Remember that claims terms are interpreted in view of the claim as a whole.
- Use flexible terms such as "about" when claiming numerical ranges (e.g., "within about 2 C" rather than simply "within 2 C").
- Provide support in the specification for numerical ranges and any potential fluctuations outside the ranges.
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Overview
In Lexion Medical, LLC v. Northgate Technologies, Inc. et al., the US Court of Appeals for the Federal Circuit (“Federal Circuit”) affirmed the district court’s grant of summary judgment of infringement in favor of Lexion, construing a claimed numerical range in Lexion’s patent to include minor fluctuations outside the claimed range.
Case Background
Lexion sued Northgate for infringement of a patent directed to a method for introducing heated and humidified gas within a particular temperature range into a patient during endoscopic surgery.
Determination of infringement was based on construction of a claim limitation involving a gas “having a temperature within 2 °C of the predetermined temperature” since Northgate’s Humi-Flow® device introduced heated and humidified gas into a patient at temperatures that fluctuated outside the claimed range.
Decision Analysis
In affirming the district court’s decision, the Federal Circuit noted that the method claims at issue not only included a specific temperature range, but also included steps for sensing the temperature of the gas as it leaves the chamber and, if the temperature is outside the claimed range, actuating a heating means to bring the gas within the claimed range.
The Federal Circuit reasoned that, because the method provides steps for correcting minor fluctuations outside of claimed range, the phrase “having a temperature within 2 °C of the predetermined temperature” should be construed to also include such fluctuations.
The Federal Circuit also found support in the specification for fluctuations outside the claimed range, such as use of the term “about” in describing the temperature range and description of a lag time in reaching the target temperature range.
Northgate’s device was found to literally infringe Lexion’s patent despite providing gas at temperatures outside the claimed range.
Takeaways
When analyzing a claim involving a numerical range, remember that claim terms are interpreted in view of the claim as a whole and in view of the specification. Although the Federal Circuit broadly interpreted the claims in this case to include minor fluctuations outside a claimed temperature range, we recommend using flexible terms such as “about” when claiming a numerical range.
It is also important to describe the claimed numerical ranges and any potential fluctuations outside the ranges in the specification.
