In the last post on claim construction, I had discussed a few preliminary principles; pursuant to requests from readers asking for concrete examples to explain the principles better, I did a bit of reading and thought it best to explain the application of the principles using judgments, instead of merely parroting a standard list of dos and donts on claim construction. I shall discuss a judgment which was delivered early this month in Exergen Corp. v. S.A.A.T Systems by the US CAFC, with the doctrine of inherent anticipation being the focal point of the judgment. I chose this because inherent anticipation being a slightly grey area, provides us with enough meat to chew on and would help in really testing one’s grasp of the concept, not to mention the ability to explain it in a lucid manner.
Before I proceed with the judgment, let’s discuss briefly the concept of anticipation by comparing and contrasting it with obviousness. Why is this CnC exercise necessary and how is it relevant to this post? This exercise is essential because it is important to understand the distinction between the concept of inherent anticipation and obviousness which requires us to go back to understanding anticipation again.
“Anticipation is a matter of fact and obviousness is a mixed issue of fact and law”, so goes the standard adage in patent law. But isn’t every issue a mixed issue of fact and law? Then why are we drawing this glorious distinction between anticipation and obviousness? What is the true import of this distinction in practice? Anticipation refers to a situation where a single document discloses each and every element claimed in an impugned patent. Why does it need to be a single document? And what is the scope of “disclosure” for the document to anticipate the patent?
The emphasis on a single document is for good reason because if a challenger to a patent relies on more than one document, then he and consequently the Court, has to look for gaps or vacuum in the information disclosed in the documents i.e. the analysis becomes one that of obviousness and not anticipation. The reason being the Court cannot rule out the possibility of the patented invention being genuinely inventive despite various elements of the invention having been disclosed expressly in disparate documents. In other words, the degree of subjectivity in an obviousness enquiry is by nature greater than in an anticipation enquiry.
Ergo, theoretically and crudely speaking, in an anticipation enquiry, what one does, is compare the elements disclosed in a document with the elements claimed in the impugned patent. This is expected to be a mere factual enquiry as opposed to obviousness where the Court dons the mantle of a person ordinarily skilled in the art to comment on the mental leap required by a practitioner to arrive at the impugned invention with state of prior art being the starting point of enquiry. But how true is this in practice? Even assuming that this is the accurate picture on the ground, how does one explain and justify the use or the very presence of the doctrine of inherent anticipation?
It must be understood that be it anticipation or obviousness, the knowledge of a person skilled in the art (aka POSITA) is a relevant factor in inferring what has been disclosed, more so when such disclosure is not express, but implicit. But how often and to what extent can this factor be used in an anticipation enquiry retaining its nature as an anticipation enquiry? This is precisely the question that one needs to answer if the doctrine of inherent anticipation is to be demystified. To find the answer, let’s move to the judgment.
Parties, Forum and Decision
Appellant/Defendant: SAAT Systems
Patentee/Respondent: Exergen Corp.
Forum: US CAFC (Courts of Appeals for the Federal Circuit)
Decision: Decision delivered in favour of the appellants
Facts of the Case
The trial court found SAAT guilty of infringement of Exergen’s US patents 5012813 (‘813), 6047205 (‘205) and 6292685 (‘685). For the purposes of our discussion, what is relevant is that the CAFC held the ‘205 patent to have been inherently anticipated by a prior US patent 4602642 (‘642) granted to another patentee and hence there could be no infringement of an invalidly granted patent.
Technology Covered by the Patents
Infrared thermometers used for measuring human body temperature were the subject-matter of these patents. The thermometers first detected the surface temperature of the human body, such as the temperature of the tympanic membrane or the skin of the forehead and related it to the internal temperature of the body after adjusting it for ambient temperature. The internal temperature was calculated based on the equations provided in the patent and was finally displayed in a digital readout which formed part of the equipment.
Discussion
The ‘205 patent disclosed a thermometer that detected radiation from the tympanic membrane but broadly claimed detection of radiation from a “biological tissue”. The thermometer manufactured by SAAT on the other hand detected radiation from the skin that covers the temporal artery which was subsequently converted to the patient’s oral temperature. Exergen alleged that SAAT’s thermometer infringed its ‘205 patent to which SAAT countered that the ‘205 patent was anticipated by the ‘642 patent.
To resolve the issue, the Court had to construe claims, which means terms had to be ascribed a particular meaning which both parties at issue would find agreeable. Let’s take a look at the independent claim of the impugned Exergen patent (‘205), which read thus:
A method of detecting temperature of biological tissue comprising:
Providing a radiation detector for sensing infrared radiation from an external target;
Sensing radiation from multiple areas of the biological tissue with the radiation detector; and
Electronically detecting the peak radiation from the multiple areas to obtain a peak temperature signal.
The key term which upon literal interpretation is wide in its ambit is “biological tissue”, precisely for this reason it is imperative that this term be imputed a specific meaning bearing in mind the context of its use. Accordingly, “biological tissue” was agreed by both parties to mean “a living layer of external human tissue having a temperature that can be measured”.
“Internal temperature” was the next term construed by the Court to mean “temperature of the region beneath the surface of the biological tissue targeted for measurement”.
Having construed the key terms in the independent claim, to establish anticipation, we would have to compare the elements claimed in the independent claim with the elements disclosed in the anticipatory literature i.e. ‘642 patent. Following are the elements of the ‘642 patent:
1. It discloses a method and apparatus for measuring the internal temperature of a patient’s body by sensing infrared emissions from the external ear canal
2. The apparatus has a probe unit which is heated for calibration upto normal human temperature i.e. 98 F by a chopper unit.
3. Upon calibration, the probe unit is detached from the heating unit (chopper unit) and has to be inserted in the external ear canal within ten seconds of detachment.
4. The probe unit records seven radiation readings per second right from the time it is detached from the heating chopper unit to the time it is inserted in the ear canal. This means that until the time it is inserted in the external ear canal it would have taken 70 readings.
5. Upon insertion, the probe unit is scanned for the maximum reading which is then displayed as the tympanic temperature.
Upon comparison of these features of the ‘642 patent with Exergen’s ‘205 patent, it might be apparent that the former anticipated the latter; but Exergen didn’t think so and following were its contentions to support its stance that ‘642 did not anticipate its ‘205 patent:
1. Since the apparatus described in the ‘642 patent had a heating unit, it meant that the probe unit measured its own radiation in addition to the radiation of the surroundings (which was not stated in express terms in the ‘642 patent); and
2. The ‘642 patent, according to Exergen, measured the radiation only from one spot i.e. the ear canal and not “multiple areas” as claimed by Exergen’s patent.
The first contention shouldn’t have been raised in the first place because it is common knowledge that the thermometer, be it in the ‘642 patent or Exergen’s impugned patent, would measure its own radiation in addition to the radiation emitted by the target surface since it was integral to the process of radiation measurement; this point was conceded by Exergen as well. Also, the Court rightly pointed out that since the term “comprising” had been used in ‘205’s independent claim, the measurement of radiation was not limited to the target surface and included self-radiation (or irradiation) as well.
As for the second contention, the Court again drew Exergen’s attention to ‘642’s specification and pointed out that the probe unit measured readings right from the time of its detachment from the chopper unit till the time it was inserted in the ear. In other words, it did measure readings from “multiple areas” and this was an indispensable feature of its working. The fact that this was not disclosed explicitly in the description did not mean that the feature was not anticipated.
Stated otherwise, a feature or an element or a fact which would per force form part of the invention’s working had to be construed as being inherently disclosed by the anticipatory literature and the absence of an express disclosure of such a necessary feature would not take away anything from the challenger’s claim of anticipation. A crude example to explain this would be that the presence of a nut indicates the presence of a bolt or a mating feature which need not be mentioned explicitly because a person skilled in the art would anyway take its presence for granted.
This is also the key distinction between inherent anticipation and obviousness. Something which a person skilled in the art would have to assume to be indispensable or necessary would fall within the scope of inherent anticipation; however, something which a POSITA may or might have done without much ingenuity on his part would fall within the scope of an obviousness enquiry.
In the next post, we shall continue our discussion on claim construction and look at a few more judgments and critiques on inherent anticipation.
