Rule 702 Expert Testimony

I may have jumped the gun in my post about expert witnesses by not first tackling the rule.  Rule 702 states:

 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:

 (a)  the expert’s scientific, technical, or other specialized knowledge is beyond that possessed by the average layperson;

 (b)  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; and

 (c)  the expert’s methodology is generally accepted in the relevant field.
This always reminds me of this great scene in My Cousin Vinny.  

There is an important case that further explains additional principles that apply to the degree of certainty required.  Kravinsky v. Glover of 1979 states,
  • An expert need not testify with absolute certainty or rule out all possible alternative causes
  • Expert testimony is admissible when, taken in its entirety, it expresses reasonable certainty that the event was a substantial factor in bringing about the harm
  • That an expert may, at some point during his testimony, qualify the assertion does not necessarily render the opinion inadmissibly speculative