This summary is not the rule. The rule text controls.
An expert witness can form their opinion using facts or information they learned about the case, whether they saw that evidence firsthand or someone told them about it. This gives experts flexibility in how they gather the information they need to reach their conclusions.
Here's the important part: experts can even rely on evidence that would not normally be allowed in court, as long as other experts in that same field would normally use that same kind of evidence to form opinions. For example, a doctor might normally rely on lab reports or notes from other medical staff, even though those documents alone might not be allowed as evidence in a trial. If it is standard practice in that profession to depend on this kind of information, the expert can still use it to support their opinion.
This rule matters because it means an expert's opinion is not thrown out just because some of the underlying information could not be presented on its own. The court trusts that experts know what reliable information looks like in their field, based on their training and experience.
