Explain the difference between an expert witness and a lay witness. Explain the situations in which each type of witness may be used.

The difference between an expert witness and a lay witness is that an expert witness has professional training and experience that qualifies him or her to testify on a particular subject.
A lay witness, on the other hand, is someone who can truthfully and accurately testify as to certain facts in question without having specialized training or knowledge. Expert witnesses are often used in medical malpractice and product liability cases to establish the duty, or standard of care, that the defendant owed to the plaintiff. Lay witnesses are the people who observed or have other information about an event or a fact and are used to testify about the same.