CALIFORNIA EVIDENCE: CIVIL AND CRIMINAL
...Opinion & Scientific Evidence
......Lay Opinion
.........Improper Subjects
............Beyond Facts Observed
4 Cards On This Topic:

Harmless error to allow police drug expert's lay interpretation of clear unambiguous statements.

Lay witness may not offer opinion that goes beyond facts personally observed.

Nothing fundamentally unfair about applying ordinary rules of evidence to exclude speculative opinion testimony, especially where an obvious other source for the same information available.

Opinion testimony may be excluded when not rationally based on witness' perceptions.