By Kevin E. Noonan --
"Everything you say can be held against you" is a trope in crime shows from the U.S., Australia, New Zealand, the UK, and Ireland (stated in various ways), and a recent decision by the Federal Circuit regarding preclusion of infringement under the doctrine of equivalents by prosecution history estoppel is an excellent example of the same principle in patent law.
The lawsuit that gave rise to the Court's decision in Pharma Tech Solutions, Inc. v. Lifescan, Inc. involved Pharma Tech's assertion of U.S. Patent Nos. 6,153,069 and 6,413,411, which were directed to blood glucose monitoring systems. As explained in the opinion:
To test blood glucose, an individual typically draws blood by pricking a finger, placing the blood on the end of a test strip, and placing the test strip into a meter. The test strip contains a pair of electrodes, including a working electrode and a second electrode. The working electrode is coated with an enzyme that oxidizes glucose in the blood sample. Following an incubation period, the meter (1) applies a known electric potential across the electrodes, creating a diffusion limiting electric current (referred to as the "Cottrell current") through the sample; and (2) measures Cottrell current. A proportional relationship exists between the measured current and blood glucose concentration. Based on this proportional relationship, a microprocessor in the meter converts the measured electric current to a blood glucose level and then reports the blood glucose level to the user.
The distinction from prior art monitoring systems embodied in the claims is illustrated by the italicized portion of claim 1 of the '069 patent:
1. An apparatus for measuring compounds in a sample fluid, comprising:
a) a housing having an access opening therethrough;
b) a sample cell receivable into said access opening of said housing, said sample cell being composed of;
(i) a first electrode which acts as a working electrode;
(ii) a second electrode which acts to fix the system potential and provide opposing current flow with respect to said first electrode, said second electrode being made of the same electrically conducting material as said first electrode, and being operatively associated with said first electrode, the ratio of the surface area of said second electrode to the surface area of said first electrode being 1:1 or less;
(iii) at least one non-conducting layer member having an opening therethrough, said at least one non-conducting layer member being disposed in contact with at least one of said first and second electrodes and being sealed against at least one of said first and second electrodes to form a known electrode area within said opening such that said opening forms a well to receive the sample fluid and to allow a user of said apparatus to place the sample fluid in said known electrode area in contact with said first electrode and said second electrode;
c) means for applying an electrical potential to both said first electrode and said second electrode;
d) means for creating an electrical circuit between said first electrode and said second electrode through the sample fluid;
e) means for measuring a first Cottrell current reading through the sample fluid at a first predetermined time after the electrical potential is applied and for obtaining at least one additional Cottrell current reading through the sample fluid, the at least one additional Cottrell current reading occurring at a second predetermined time following the first predetermined time;
f) microprocessor means for converting the first Cottrell current reading into a first analyte concentration measurement using a calibration slope and an intercept specific for the first Cottrell current measurement, for converting the at least one additional Cottrell current reading into an additional analyte concentration using a calibration slope and an intercept specific for the at least one additional Cottrell current measurement, and for comparing the first analyte concentration measurement with the at least one additional concentration measurement to confirm that they are within a prescribed percentage of each other; and
g) means for visually displaying the results of said analyte concentration measurements.
Thus, rather than measuring the induced Cottrell current readings and comparing them, the microprocessor converts these current readings to glucose concentrations and compares them.
Lifescan's accursed infringing article, sold as the OneTouch® Ultra® system, operates by measuring current produced in the presence of blood on the test strip in two working electrodes during a five-second "countdown period," and then conducts a "Current Difference Test" (as a control that the values are within proscribed limits), followed by calculating total final current (that is then correlated with blood glucose concentration). As stated in the opinion:
It is undisputed that Lifescan's meters neither convert multiple Cottrell current readings to analyte concentration measurements nor compare multiple analyte concentration measurements. Pharma Tech agrees that the accused products therefore do not literally infringe the claim. But Pharma Tech asserts that "an analyte measurement can be expressed as a current at a given time or as a concentration" and, thus, the accused device infringes under the doctrine of equivalents.
The opinion sets forth certain aspects of the prosecution history, wherein the italicized portion of the claim set forth above was added by amendment in response to rejection over certain prior art references (specifically U.S. Patent No. 5,385,846 (Kuhn), U.S. Patent No. 5,288,636 (Pollmann), and U.S. Patent No. 5,108,564 (Szuminsky)). These amendments were accompanied by argument, wherein the applicant relied on the feature of converting the Cottrell current readings to analyte (i.e., blood glucose) concentrations which were then compared with one another. These amendments were not completely availing for patentability, because the Examiner asserted two additional prior art references (U.S. Patent No. 5,508,171 (Walling) and U.S. Patent No. 5,243,516 (White)) for obviousness, which the applicant distinguished based on the "converting" and "comparing" language introduced into the claims in the previously presented amendment. After somewhat protracted argument along these lines, the applicant was finally able to have the '069 patent grant; the '411 patent granted shortly thereafter.
The District Court granted Life Scan summary judgment that prosecution history estoppel prevented Pharma Tech from showing infringement under the doctrine of equivalents (Pharma Tech dismissed its literal infringement claims). In doing so, the Court held that both amendment-based and argument-based estoppel arose by Pharma Tech's amendments and arguments, and rejected plaintiff's argument that estoppel did not arise because the amendments and arguments were only tangentially related to patentability, pursuant to Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 344 F.3d 1359, 1369 (Fed. Cir. 2003). This appeal followed.
The Federal Circuit affirmed, in an opinion by Judge Stoll, joined by Judges Moore and Reyna. The opinion sets forth the parameters of "amendment-based" estoppel (that the amendment was narrowing for purposes of establishing patentability over the prior art) and "argument-based" estoppel (surrender of claim scope by arguments made to the Patent Office), finding both species of estoppel on the record before it. Under Festo, a presumption arises when an applicant submits a narrowing amendment to overcome a rejection for unpatentability. That presumption can be overcome one of three ways, according to the Court: "(1) the equivalent was "unforeseeable at the time of the application"; (2) "the rationale underlying the amendment may bear no more than a tangential relation to the equivalent in question"; or (3) "there may be some other reason suggesting that the patentee could not reasonably be expected to have described the insubstantial substitute in question," citing Festo at 740-1. Here, Pharma Tech argued tangentiality, unsuccessfully.
With regard to argument-based estoppel, "the prosecution history must evince a clear and unmistakable surrender of subject matter" according to the opinion, citing Conoco, Inc. v. Energy & Envtl. Int'l, L.C., 460 F.3d 1349, 1364 (Fed. Cir. 2006) (quoting Deering Precision Instruments, L.L.C. v. Vector Distribution Sys., Inc., 347 F.3d 1314, 1326 (Fed. Cir. 2003)). The Court set forth the policy bases for this estoppel, stating that "[c]lear assertions made during prosecution in support of patentability, whether or not actually required to secure allowance of the claim, may also create an estoppel . . . because [t]he relevant inquiry is whether a competitor would reasonably believe that the applicant had surrendered the relevant subject matter," citing PODS, Inc. v. Porta Stor, Inc., 484 F.3d 1359, 1368 (Fed. Cir. 2007).
The Federal Circuit held that both types of estoppel precluded Pharma Tech from a finding of infringement under the doctrine of equivalents. Regarding amendment-based estoppel, the opinion states that, prior to amendment Pharma Tech's claim "was broad enough to cover any bioelectrical blood glucose monitoring system" and afterwards, the claim was limited to systems that converted Cottrell current readings to analyte concentrations that were compared to one another. Accordingly, "[t]he applicants thus presumptively surrendered any bioelectrical blood glucose monitoring systems that do not convert a plurality of current readings into analyte concentration measurements and compare the resulting analyte concentration measurements." The "equivalent" asserted by Pharma Tech to ensnare Lifescan's accused infringing article -- "the functionality of a system that (a) measures current at two different times, (b) compares the current[s] to ensure they are within a prescribed percentage and (c) converts the current readings into a glucose concentration" -- "falls squarely within the territory between the original claim and the amended claim" in the panel's view. In order for Pharma Tech to overcome the presumption that the amendments estopped them from (successfully) asserting this equivalent, its burden was to show that the amendment was only tangentially related to patentability. Pharma Tech failed to make this showing, according to the opinion, because "the inventors clearly and unambiguously distinguished their invention over the prior art based on the converting and comparing limitations added by [their] amendment." The opinion cites the "consistent[] assert[ions]" (expressly cited in the opinion) by the patent applicant that their amendment overcame the asserted prior art in support for their conclusion regarding amendment-based estoppel. And to Pharma Tech's argument that their amendment (under the Court's reading) surrendered more claim scope than necessary to establish patentability, the opinion states that this doesn't establish tangentiality, citing Int'l Rectifier Corp. v. IXYS Corp., 515 F.3d 1353, 1359 (Fed. Cir. 2008) (quoting Schwarz Pharma, Inc. v. Paddock Labs., Inc., 504 F.3d 1371, 1377 (Fed. Cir. 2007)) that "'[t]he fact that the inventors may have thought after the fact that they could have relied on other distinctions in order to defend their claims is irrelevant' to discerning the objective reason for their amendment."
As for argument-based estoppel, the opinion states that Pharma Tech failed to show that the facts before the panel were sufficiently analogous to cases where the estoppel was not found to absolve these claims from this species of estoppel. Specifically, the opinion rejects Pharma Tech's attempted reliance on Insituform Technologies, Inc. v. CAT Contracting, Inc., 385 F.3d 1360 (Fed. Cir. 2004). In that case, the Federal Circuit was able to find that there was "no indication in the prosecution history of any relationship between the narrowing amendment" and the asserted equivalent. Here, in contrast, the Court found ample evidence that the amendments and arguments had more than a tangential relationship to patentability. Similarly, the panel distinguished these facts from the situations arising in recent Federal Circuit decisions regarding the scope of estoppel, including Eli Lilly & Co. v. Hospira, Inc., 933 F.3d 1320, 1332 (Fed. Cir. 2019) and Ajinomoto Co. v. Int'l Trade Comm'n, 932 F.3d 1342, 1355 (Fed. Cir. 2019).
The outcome here illustrates the difficulty (if not impossibility) of predicting future design-around efforts by others, and how prudent prosecution practices include maintaining pending applications to give a patentee the flexibility to pursue claims that will be literally infringed by even the most clever competitors.
Pharma Tech Solutions, Inc. v. Lifescan, Inc. (Fed. Cir. 2019)
Panel: Circuit Judges Moore, Reyna, and Stoll
Opinion by Circuit Judge Stoll
The opinion: "It is undisputed that Lifescan's meters neither convert multiple Cottrell current readings to analyte concentration measurements nor compare multiple analyte concentration measurements." What about the "same way" DOE requirement?
1. Performs substantially the same function
2. In substantially the same way
3. To obtain the same result
as the limitation literally recited in the patent claim. See Graver Tank & Manufacturing Co. v. Linde Air Products Co., (1950).
Posted by: Paul F. Morgan | November 28, 2019 at 09:36 AM
Paul: I think there could have been an issue with #2 (depending on the granularity of the analysis), but both the district court and Federal Circuit addressed the PHE issue (which was enough to preclude equivalents).
Thanks for the comment, and Happy Thanksgiving.
Posted by: Kevin E Noonan | November 28, 2019 at 09:04 PM
Mr. Morgan,
Elsewhere there appears to be a huge wailing and whining about how "out of control" or how "uncertain" DoE plays out.
And yet, as you point out here, the actual application of DoE (apart from whether any SINGLE individual application of such has been fully carried out) seems, well, abundantly straight forward.
It is not all that surprising the people raising such as an issue (and their other well known stances towards strong innovation protection systems).
Posted by: skeptical | November 29, 2019 at 12:14 PM