Kingsdown (plaintiff) sued Hollister (defendant) for infringement of the ‘363 patent, which claimed a medical device used to release waste in patients with openings in their abdominal walls. The patent prosecution took several years, and included numerous claims, amendments, prior art references, correspondence and other documents. Finally, Kingsdown reached a point in prosecution where the patent examiner indicated that certain claim language would be allowable, specifically original claim 50. Claim 50 as originally filed was rejected for being indefinite, an error readily corrected through an amendment by Kingsdown’s patent counsel at the time. After this news from the examiner, Kingsdown learned of a Hollister medical device that was believed to infringe the claims. Kingsdown filed a continuation application in an effort to obtain as much allowable subject matter as possible in short order to pursue Hollister. In so doing, the Kingsdown patent attorney submitted a new set of claims to the patent examiner, including a listing of new claims that corresponded to earlier claims deemed allowable by the examiner. However, an error was made, and the patent attorney included rejected claim 50 as originally filed instead of amended claim 50, which was later filed as claim 43, and indicated that it had been allowed. This error escaped everyone and the patent issued. Hollister alleged that the entire patent was invalid for inequitable conduct before the patent office, based on the gross negligence of the patent attorney and the looming threat of the Hollister device. The district court, reasoning that the examiner could have relied on the representation that new claim 43 was amended claim 50, instead of the original rejected claim 50, held the patent invalid. Specifically, the district court held that, because Kingsdown filed amended claims only after reviewing the Hollister accused product, deceptive intent could be inferred. Kingsdown appealed.