U.S. v. Christian

In prosecution on firearm charge, Dist. Ct. did not commit plain error in permitting police officer to testify as both expert and fact witness regarding defendant's actions at arrest scene, when officer told jury that defendant had concealed his hands from officer and when officer gave opinion that defendant's actions were consistent with possession of gun. While Dist. Ct. should have cautioned jury to separate officer's factual testimony from his expert opinion testimony and should have required prosecutor to make jury clear as to when officer was testifying as expert, no reversible error occurred where Dist. Ct. gave standard instruction for opinion testimony, and where defendant otherwise had opportunity to cross-examine officer regarding what he actually saw at arrest scene.