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Exergen Corporation v. Kaz USA, Inc.

Representative Claim(s)

‘685 patent

  1. A body temperature detector comprising:

a radiation detector;

and electronics that measure radiation from at least three readings per second of the radiation detector as a target skin surface over an artery is viewed, the artery having a relatively constant blood flow, and that process the measured radiation to provide a body temperature approximation, distinct from skin surface temperature, based on detected radiation.

  1. The body temperature detector of claim 48 wherein the artery is a temporal artery.

’938 patent,

  1. A method of detecting human body temperature comprising making at least three radiation readings per second while moving a radiation detector to scan across a region of skin over an artery to electronically determine a body temperature approximation, distinct from skin surface temperature.
  2. The method of claim 14 wherein the artery is a temporal artery.


Appeal from United States District Court for the District of Massachusetts. The District Court found that claims were directed to a patent-eligible subject matter.

Exception Category: Law of Nature

“There is no dispute in this case that the asserted claims employ a natural law to achieve their purpose. The claims recite a ‘method of detecting human body temperature”’ and ’a body temperature detector’ which generally utilize temperature readings from the forehead skin and the ambient temperature to calculate an approximate core body temperature. See, e.g., ’685 patent at claim 17; ’938 patent at claim 60. And a significant portion of the specification is dedicated to deriving the mathematical equations to calculate core temperature based on ambient and skin temperature readings. ’685 patent at 6:58–8:45. What the parties dispute, however, is whether the additional claimed steps beyond calculating the temperature present a novel technique in this computation or add an inventive concept sufficient to transform the claims into a patent-eligible application.”

Significantly More: Yes

“The district court reasoned that ‘while the asserted claims are based in natural phenomena,’ the claims recite additional steps which, like the claims in Diamond v. Diehr, 450 U.S. 175 (1981), ‘transformed the underlying natural laws into inventive methods and useful devices that noninvasively and accurately detect human body temperature.’ … The court noted that the asserted claims each recite a subset of three steps: (1) moving while laterally scanning… (2) obtaining a peak temperature reading … and (3) obtaining at least three readings per second.  … The district court found that though these claim elements may have been known in the art, they were ‘previously utilized to detect hot spots indicating injury or tumors, or surface temperature differentials,’ not used to solve the problem of detecting arterial temperature beneath the skin.  … After considering all the trial testimony and evidence, the district court found that “’there is no evidence in the record’ that these methods were well-understood, routine, and conventional prior to the introduction of Exergen’s invention.”

“The question of whether a claim element is well-understood, routine, and conventional to a skilled artisan in the relevant field is a question of fact and deference must be given to the determination made by the fact finder on this issue. Something is not well-understood, routine, and conventional merely because it is disclosed in a prior art reference. There are many obscure references that nonetheless qualify as prior art. For example, we have held that a single copy of a thesis written in German and located in a German university library was a printed publication because that thesis was available to the public. In re Hall, 781 F.2d 897, 897–900 (Fed. Cir. 1986). This type of evidence, for example, would not suffice to establish that something is ‘well-understood, routine, and conventional activity previously engaged in by scientists who work in the field.’ Mayo, 566 U.S. at 79.”

“Here, the patent is directed to the measurement of a natural phenomenon (core body temperature). Even if the concept of such measurement is directed to a natural phenomenon and is abstract at step one, the measurement method here was not conventional, routine, and well-understood. Following years and mil-lions of dollars of testing and development, the inventor determined for the first time the coefficient representing the relationship between temporal-arterial temperature and core body temperature and incorporated that discovery into an unconventional method of temperature measurement. As a result, the method is patent eligible, similar to the method of curing rubber held eligible in Diehr. In other words, at the second step of Mayo/Alice, the patent incorporated an inventive concept. The same is true here.”

Judge Hughes dissented:

“We determine whether a patent claims eligible subject matter under 35 U.S.C. § 101 through a two-step test. Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66 (2012). At step one, we determine whether the claims are directed toward a patent-ineligible concept. Alice Corp. Pty. v. CLS Bank Int’l, 134 S. Ct. 2347, 2355 (2014). If so, we consider at step two whether the claims nonetheless embody a sufficiently inventive concept to transform the claimed invention into a patent-eligible application. Id. (quoting Mayo, 566 U.S. at 78).”

“The majority reaches step two, affirming the district court’s determination that the claims of the ’685 and ’938 patents embody inventive concepts. In my view, the claimed inventions merely calculate a law of nature using conventional, commercially available technology. Following the principle that well-understood, routine, and conventional activities cannot supply an inventive concept, I would find the asserted claims are patent ineligible under § 101. Thus, I respectfully dissent from the majority’s conclusion that the asserted claims are patent eligible.”

“The asserted claims begin and end with a law of nature. … Even under a deferential standard of review, the district court clearly erred by finding that the claims of the ’685 and ’938 patents embody an inventive concept. … Temperature-detecting products that make use of [the recited] elements have existed for decades.  … At the time of invention, the combination of these elements into a single product was also well-known.”

“In reaching the opposite conclusion, the district court legally erred by using a law of nature to supply an inventive concept. The district court never found that the combination of taking multiple measurements while scanning laterally across the forehead to determine peak temperature was not well-understood, routine, and conventional. It only found that there was ‘no evidence … that these steps were ‘well-understood, routine, [or] conventional[ly]’ used to detect arterial temperature beneath the skin.’ Rather than finding that the claim elements were not routine or conventional, the district court focused on whether those elements were routinely or conventionally used for the purpose of calculating core body temperature. It differentiated the claimed invention from the prior art solely on the basis that the claimed invention ‘solve[s] a different problem.’ ”

“We rejected identical reasoning in Ariosa. There, the patentee argued its claimed methods of amplifying and detecting paternal cffDNA in maternal plasma supplied an inventive concept because such methods had never been used on maternal plasma samples. We noted that the claimed cffDNA amplification and detection methods were well-understood, routine and conventional. As a result, the patentee’s argument implied that the inventive concept lied solely in the natural phenomenon that paternal cffDNA exists in maternal plasma. Although the claimed methods solved a novel problem, using conventional techniques for a new purpose did not supply an inventive concept that amounted to significantly more than the natural phenomenon to which the claims were directed.”

The majority’s “…reasoning that Exergen’s temperature detector is ‘unconventional’ at step two because it uses ‘for the first time the coefficient representing the relationship between temporal-arterial temperature and core body temperature.’ The majority’s analysis fails to identify any combination of claim elements that is not well-understood, routine, and conventional aside from the use of a newly discovered law of nature. This is unsurprising because the prior art contains temperature detectors like DermaTemp that incorporate every element of the claimed invention besides the heat balance equation. To overcome the claimed invention’s lack of an inventive concept, the majority opinion erroneously conflates step two with a novelty inquiry.”