The en banc Federal Circuit on May 25, 2011, held by a 6-1-4 vote that the materiality required to establish inequitable conduct is but-for materiality in most cases. Therasense Inc. v. Becton Dickinson and Co., Fed. Cir. en banc, No. 2008-1511, 5/25/2011. Unlike validity defenses, which are claim specific, see 35 U.S.C. § 288, inequitable conduct regarding any single claim renders the entire patent unenforceable. The remedy for inequitable conduct is the “atomic bomb” of patent law. Aventis Pharma S.A. v. Amphastar Pharm., Inc., 525 F.3d 1334, 1349 (Fed. Cir. 2008). Judge Rader noted:
Left unfettered, the inequitable conduct doctrine has plagued not only the courts but also the entire patent system. Because allegations of inequitable conduct are routinely brought on “the slenderest grounds,” Burlington Indus., 849 F.2d at 1422, patent prosecutors constantly confront the specter of inequitable conduct charges. With inequitable conduct casting the shadow of a hangman’s noose, it is unsurprising that patent prosecutors regularly bury PTO examiners with a deluge of prior art references, most of which have marginal value.
Non-disclosed prior art is but-for material if the patent examiner would not have allowed a claim had it been aware of the undisclosed prior art, according to the opinion rendered by Chief Judge Rader.
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