How has the Court treated the Government's rebuttal summation?

and conversations upon which a conclusion was based than to a mere statement by the accused of his conclusion, unsupported by such statements. Miller v. United States, 120 F.2d 968, 97071 (10th Cir.1941).

The comments in the Government's rebuttal summation were troubling as well. We recognize that summations, and particularly rebuttal summations, are not fully constructed in advance. See Donnelly v. DeChristoforo, 416 U.S. 637, 64647, 94 S.Ct. 1868, 40 L.Ed.2d 431 (1974). But the improvisatory nature of a rebuttal summation is no license for improper vouching, referencing facts not in the record, or appealing to extraneous consequences of a verdict.