Is a plea of not guilty in a trial to the bench a functional equivalent of a motion for acquittal in a jury trial?

Ordinarily we would not hesitate to express agreement with our sister circuits that a plea of not guilty in a trial to the bench is the functional equivalent of a motion for acquittal in a jury trial. In a bench trial, the judge acting as the trier of both fact and law implicitly rules on the sufficiency of the evidence by rendering a verdict of guilty. A motion to acquit is superfluous because the plea of not guilty has brought the question of the sufficiency of the evidence to the court's attention. The government wisely conceded this point at oral argument. We must, however, first confront our earlier opinion in United States v. Floyd, 945 F.2d 1096 (9th Cir.1991), amended, 956 F.2d 203 (9th Cir.1992).