An Expert Witness Give an Opinion If

An Expert witness give an opinion if:

A) The Opinion, inferences or conclusions depend on special knowledge, skill or training not within the ordinary experience of lay jurors
B) To define the issues of the case for determination by the finder of fact
C) To stimulate discussion between the consulting expert and the expert witness
D) To deter the witness form expanding the scope of his or her investigation beyond the requirements of the case