4.14 OPINION EVIDENCE, EXPERT WITNESS
You have heard testimony from persons who, because of education or experience, were permitted to state opinions and the reasons for their opinions.
Such opinion testimony should be judged like any other testimony. You may accept it or reject it, and give it as much weight as you think it deserves, considering the witness’s education and experience, the reasons given for the opinion, and all the other evidence in the case.
See Fed. R. Evid. 701-05. See also United States v. Mendoza, 244 F.3d 1037, 1048 (9th Cir.2001) (instruction should be given when requested by the defendant).