What is the standard of review for determining whether a finding by a federal court in a civil case is erroneous?

We review de novo questions of law and mixed questions of law and fact, and generally apply a "clearly erroneous" standard to the factual findings of the district court. United States v. English, 629 F.3d 311, 319 (2d Cir. 2011). The district court's ultimate finding "may be subject to plenary review if it rests on a predicate finding which reflects a misperception of a legal rule applicable to the particular factor involved." Id. at 319-20 (quoting United States v. Shakur, 817 F.2d 189, 197 (2d Cir. 1987)).