It should have been a cakewalk. Arnold & Porter Kaye Scholer counsel Krista Carter strode into the U.S. Court of Appeals for the Federal Circuit on Feb. 10 to defend what on the surface looked like a bulletproof $500,000 patent infringement judgment.

U.S. Magistrate Judge Donna Ryu of Oakland, California, had granted summary judgment of patent validity for Carter’s client, AAT Bioquest Inc. Opponent Texas Fluoresence Laboratories conceded infringement.