Elk Corp. of Dallas v. GAF Building Materials Corp., 98-1369, 1999 U.S. App. LEXIS 2036 (Fed. Cir. Feb. 11, 1999).




Whether the trial court erred by holding Elk Corporation's ("Elk") U.S. Design Patent No. 344,144 (the '144 patent) unenforceable for inequitable conduct before the Patent Office by Elk and its patent attorney during the prosecution of the patent.


No. Elk's design patent is unenforceable due to inequitable conduct because material prior art patents that Elk was aware of were intentionally left undisclosed during prosecution of the '144 patent.


Elk brought a patent infringement suit in federal district court against GAF Building Materials Corp. ("GAF"), alleging infringement of the '144 patent. GAF counterclaimed, seeking a declaratory judgment that the '144 design patent was unenforceable for inequitable conduct before the PTO. GAF alleged Elk and its patent attorney intentionally withheld from the examiner with the intent to mislead two material prior art patents, the Bettoli patent (U.S. Patent No. 3,921,358) and the Giles patent (U.S. Patent No. 2,036,329). GAF also alleged that Elk offered arguments to the examiner to overcome an initial rejection that Elk could not have made had it disclosed these two patents. The district court accepted GAF's arguments and held the '144 patent unenforceable for inequitable conduct.

The Court of Appeals for the Federal Circuit affirmed the district court's decision holding that, in failing to disclose the Bettoli and Giles patents, Elk intentionally withheld with an intent to mislead material information from the PTO. The court reiterated the standard for inequitable conduct by stating that inequitable conduct must be proven by "clear and convincing evidence of (1) prior art that was material; (2) knowledge chargeable to an applicant of that prior art and of its materiality; and (3) failure of the applicant to disclose the art resulting from an intent to mislead the PTO." Elk at para. 9.

The court found that the Bettoli and Giles patents were material because there was a "substantial likelihood that a reasonable examiner would have considered the information important in deciding whether to allow the application to issue as a patent." Elk at para. 13.  In addition, the Court rejected Elk's argument that the two patents were cumulative of other patents disclosed to the Patent Office during prosecution of the '144 patent and thus need not have been disclosed. Further, the court stated that the element of intent for inequitable conduct purposes may be inferred from the facts and circumstances. The Court found that Elk's intent to mislead could be inferred in light of the surrounding circumstances. Thus, the Federal Circuit held that the district court did not err in holding the '144 patent unenforceable for inequitable conduct.