An expert witness may testify in the form of an opinion, unlike lay witnesses who are generally limited to facts they perceived. Qualification rests on knowledge, skill, experience, training, or education relevant to the subject.

Experts fall into categories with different disclosure obligations: retained experts engaged for litigation, non-retained experts such as treating physicians, and consulting experts who advise counsel without testifying.

Alternative Names:

Testifying Expert, Expert

Why it Matters?

In complex litigation, expert testimony often is the case. Causation in toxic tort and medical malpractice, defect in product liability, and future damages in catastrophic injury all require expert proof, which means excluding an opponent's expert frequently ends the claim. Expert strategy therefore starts at the pleading stage rather than at the disclosure deadline.

Frequently asked questions

What qualifies someone as an expert?

What qualifies someone as an expert?

Knowledge, skill, experience, training, or education sufficient to help the factfinder. Formal credentials are common but experience alone can qualify a witness in many fields.

Can a treating physician give expert opinions?

Can a treating physician give expert opinions?

Yes, as a non-retained expert, though the scope is generally limited to opinions formed during treatment and disclosure requirements are lighter than for retained experts.