The U.S. Court of Appeals for the Federal Circuit handed out some black marks Thursday to Regeneron Pharmaceuticals Inc. and its litigation counsel at Irell & Manella.

The appellate court upheld a New York federal judge's caustic 2015 ruling that tagged the New York-based biotech company with inequitable conduct at the U.S. Patent and Trademark Office. U.S. District Judge Katherine Forrest had ruled that Regeneron's subsequent misconduct during patent infringement litigation supported the finding that the company deliberately deceived the PTO. “That which was obtained by misconduct ends as a result of misconduct,” Forrest had ruled.

An Irell team led by partners David Gindler and Jason Sheasby represented Regeneron during much of the district court proceedings. Fitzpatrick, Cella, Harper & Scinto took over midway through, and Regeneron's patent prosecution firm, Foley Hoag, also participated. An Irell spokeswoman did not immediately return a phone call seeking comment.