Is opinion testimony admissible in a criminal prosecution?

Opinion testimony by an expert is admissible in a criminal prosecution "in circumstances where it will assist the jury to understand the evidence or a concept beyond common experience." (People v. Torres (1995) 33 Cal.App.4th 37, 45.) An expert, however, "may not express an opinion on a defendant's guilt. [Citations.] The reason for this rule is not because guilt is the ultimate issue of fact for the jury, as opinion testimony often goes to the ultimate issue. [Citations.] 'Rather, opinions on guilt or innocence are

Page 6