Rule 703 Bases of Opinion Testimony by Experts

When an expert witness gives their opinion in court, they can base that opinion on two types of information. They can use facts they personally observed or gathered themselves, or they can use evidence that has already been presented in the case.

For example, a doctor who treated an injured person can share their opinion based on what they saw firsthand. An expert who was not directly involved can still give an opinion based on the evidence the court has already accepted into the record.