In Aventis Pharma S.A. vs. Hospira Inc., Fed. Cir. App. No 2011-1018, April 9, 2012, the Federal Circuit affirmed a judgment of inequitable conduct rendered after a bench trial. Significantly, that judgment was rendered prior to the Federal Circuit’s opinion in Therasense Inc. v. Becton, Dickinson & Co., 649 F.3d 1276 (Fed. Cir. 2011) (en banc). After Therasense, practitioners rightly wondered whether an inequitable conduct defense remained viable. It now appears that the defense is alive and well and will be upheld on appeal if supported by appropriate findings of fact.

Since its creation in 1982, the Federal Circuit has repeatedly addressed the inequitable conduct defense, progressively making it more difficult to plead and prove. These efforts reached their high point in Therasense where the en banc Court eliminated the “sliding scale” approach to balancing materiality and intent—the stronger a showing of one, the less of a showing needed for the other. Under Therasense, prior art has to be “but-for” material, and the intent has to be the specific intent to deceive the Patent Office. Prior art that would properly result in invalidation of a claim would necessarily be “but-for” material. With respect to intent, it must be shown that the applicant knew of the reference and its materiality and made the deliberate decision to withhold it with the specific intent to deceive the Patent Office. Such intent must be the single most reasonable inference to be drawn from the evidence. Because materiality and intent were separate and discrete elements, the “sliding scale” approach was improper.

In Aventis, supra, the references were but-for material because the trial court had properly found the claims to be invalid over them. In finding that the inventor withheld the references with the specific intent to deceive the Patent Office, the trial court rejected the inventor’s contentions that there was more than one inference that could be drawn from his conduct and found the inventor’s testimony explaining why he withheld the prior art to be not credible.

The claimed invention dealt with the chemotherapy cancer drug docetaxel which was administered in an aqueous solution. In the prior art, the surfactant Cremophor was used to form the solution. However, this substance triggered allergic reactions, including anaphylactic shock. The two patents in issue related to the use of surfactants other than Cremophor and to decreasing the amount of ethanol to reduce alcohol intoxication and the anaphylactic effects on patients. One prior art reference disclosed the use of a polysorbate as a surfactant with another cancer drug. The inventor had testified that this reference was not cited because the experiments that he and his co-inventors performed with docetaxel resulted in solutions that did not demonstrate eight hours of stability and accordingly were judged to be failures. The trial court found it telling that the inventors had cited a prior art reference which identified the problem they sought to solve, but did not cite another reference which revealed the solution to the problem. With respect to the inventor’s contention that the use of polysorbate was a failure, the trial court indicated that the inventor had only discussed tests that demonstrated low stability and did not discuss other experiments he conducted that demonstrated high stability.

The inventor had sought to explain away the other reference by indicating that the pertinent sentence disclosing the combination of polysorbate 80 and docetaxel had been added after he reviewed a draft of the article. The trial court found this testimony not to be credible and to be inconsistent with other aspects of the inventor’s testimony.

Aventis shows that where a lower court makes discrete, findings of fact establishing but-for materiality and specific intent to deceive the Patent Office, does not use a sliding scale and finds the inventor and his testimony to be not credible, there is a high probability that the Federal Circuit will affirm those findings and hold that the patent in issue is unenforceable. In other words, inequitable conduct post-Therasense is a viable defense even if it is difficult to establish.