The opinions and conclusions of an expert witness may be based upon information gained in three ways. Describe the three ways.

Question

What will be an ideal response?

Answer 1

The opinions and conclusions of an expert witness may be based upon information gained in one of three ways. First, specific information possessed by the expert, gained through examination of a particular piece of evidence, may be the basis of his or her opinion or conclusion. Such opinion testimony may be elicited simply by asking the expert what conclusions were reached after examining the evidence.
Second, the expert may rely upon data supplied from another source in any form, as long as it is within the usual practice in the field to rely on such data. Moreover, under Federal Rules of Evidence 703, the facts or data upon which the expert bases an opinion need not be admissible at trial, provided that such data or facts are of a type reasonably relied upon by experts in that field.
Third, the expert may be presented with a set of hypothetical facts from which the expert is asked to draw conclusions. This type of presentation is not used frequently in criminal cases. Most often, expert testimony in criminal cases results from an actual examination of a piece of physical evidence. This is particularly true of testimony given by criminalists. A criminalist's appearance as an expert witness generally originates from an earlier examination of an article found at a crime scene. This does not preclude the defense attorney, or the prosecuting attorney, from also presenting certain hypothetical questions to the expert.