Rule 702 - Testimony by Expert Witnesses(a) A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue.(b) Expert scientific testimony is admissible only if the court is satisfied that the expert testimony rests upon reliable scientific principles.