Opinion
A witness's inference or conclusion; admissible from lay witnesses if rationally based on perception, and from experts if qualified and reliable.
Lay opinions are limited to everyday inferences a normal person could draw from observation. Expert opinions require that the witness be qualified, the testimony rest on sufficient facts and reliable methods reliably applied (Daubert), and that it help the trier of fact. Experts may rely on inadmissible facts if experts in the field reasonably would.