In U.S. v. Cain, No. 04-15754 (Dec. 29, 2005), the Court (Anderson, Black, Carnes) the Court held that Booker error was not harmless even when the district court imposed a sentence at the top of the Guidelines range.
After the jury convicted Cain of being a felon in possession of a firearm, at sentencing the district court imposed a sentence enhancement based on evidence, not presented to the jury, that the firearm in question was stolen. The government argued that any Booker error was harmless, because the district court imposed a sentence at the top of the Guideline range, which created an inference that it would have imposed the same sentence under an advisory, post-Booker, guideline system.
Rejecting this argument, the Court held that "inference alone" does not show an error was harmless, which requires the government to "point to a statement by the district court indicating that it would have imposed the same or a higher sentence if it had possessed the discretion to do so." In the absence of such a statement, the Court of Appeals does not know what the sentence would have been, and the error is therefore not harmless. The Court vacated the sentence and remanded for resentencing.