People often mix up a fact witness with an expert witness, but they serve very different roles. A fact witness talks about what they personally saw, heard, did, or experienced. An expert witness gives opinions based on specialized training, education, or technical knowledge. So, a bystander who saw a crash on the Cross Bronx Expressway is a fact witness; an accident reconstruction engineer brought in later to explain how the impact happened is an expert witness.

A fact witness is there to provide firsthand information, not analysis. That can include a driver, passenger, coworker, police officer, or treating doctor describing care that was actually provided. What matters is personal knowledge. If the witness starts guessing or offering technical opinions outside that firsthand knowledge, the court may limit that testimony.

In an injury claim, fact witnesses can make or break disputed points like how an accident happened, whether someone looked hurt at the scene, or what conditions were like during heavy snow on I-90 near Buffalo. Their statements often influence liability, damages, and credibility.

In New York, fact witnesses may be questioned in depositions and required to appear by subpoena under CPLR Article 23. Expert disclosure is specifically addressed by CPLR 3101(d), while fact witnesses usually come into the case through ordinary discovery and witness lists rather than formal expert disclosure rules.