How have the courts treated improper statements in the opening and closing statements of a civil trial?

be sure, the district court sustained defense objections to the prosecutor's improper remarks in the Government's opening, while making clear that credibility determinations were for the jury alone to make. But improper bolstering continued into later stages of the trial without similarly "emphatic" curative steps. United States v. Friedman, 909 F.2d 705, 710 (2d Cir. 1990). As for the three concededly improper comments in the Government's rebuttal summation, the district court sustained two objections, but overruled the objection to the prosecutor's impermissible reference to the "consequences" of the jury's verdict. And the jury instructions included only standard charges on the nature of evidence, the testimony of government witnesses, and the burdens of proof, with no special curative charges.