It is improper for counsel to vouch for a witness’s credibility in closing argument in either a civil or a criminal case.  Impermissible vouching occurs when a government lawyer places the government’s prestige behind a witness through personal assurances of the witness’ veracity or when asks the jury to draw an inference of the witness’ veracity from evidence not presented to the jury—such as that police officers are credible because lying on the stand would risk losing their jobs or pensions.  However, the judgment in this case is not reversed since plaintiff’s counsel did not object to the statement and the district court did not commit clear error in failing to strike it sua sponte since prior decisions had not clearly held that the no-vouching rule applies to civil litigation.

Ninth Circuit Court of Appeals (Paez, J.; Bea, J., concurring in part & dissenting in part); September 7, 2016; 2016 WL 4651407