Is Rule 52(b) of the Federal Rule of Criminal Procedure 52(B) mandatory for a jury to acquit a defendant who failed to identify the crime during the trial?

As an alternative ground for affirming, assuming the error is plain, we exercise our discretion to disregard it because it was not brought to the attention of the district court, and does not harm the fairness, integrity or public reputation of judicial proceedings. Olano holds that Federal Rule of Criminal Procedure 52(b) is "permissive, not mandatory." 507 U.S. at 735. We may conclude that a forfeited error is plain and affects substantial rights, but we need not reverse if the error does not " 'seriously affect [ ] the fairness, integrity or public reputation of judicial proceedings.' " Id. at 736 (quoting United States v. Atkinson, 297 U.S. 157 (1936)). The "during" aspect of the crime was instructed on earlier in 27 and 27a, and the likelihood of jury confusion or error on this point is, in the factual and instructional context, negligible.