[Editor's note: One of the non-substantive attacks that certain prosecutor's use is to try to paint the expert called by the defense as a "hired gun" or a "whore" who will say anything for money. This is a regrettable tactic that has no substantive merit to the case itself and does little to promote the prosecutor's role which is to promote justice. In a discussion about this topic, Attorney Kirby Riffel offered his thoughts on the matter. I thought it was a great perspective and worthy of sharing. He agreed to write this guest blog. It is shared with you.]
Ethical and non-ethical challenges to expert witnesses
By Kirby Riffel 
I continue to believe that the best answer by the expert is to explain the nature of science to the jury. I shall attempt to illustrate imperfectly this concept. Perhaps the best answer would be as follows:
Mr. Prosecutor I think you misunderstand the nature of a scientific discipline. In the pursuit of truth, it is necessary to identify a group of persons who have gone to the trouble to acquire academic credentials within a certain field. This assures that such persons have been exposed to a body of knowledge acquired over perhaps centuries that by trial and error expresses the insights that our discipline has developed. A Ph.D. is a symbol of that accomplishment. Having achieved such an education, people like me are employed as either teachers, researchers or practitioners. We attempt through our experience and in interaction with our peers to advance, to understand this knowledge in a practical sense, to acquire the respect of our fellows and perhaps advance our collective understanding. Being board certified or a tenured faculty member (or contributing to the literature, etc.) is evidence of successful application of that knowledge and experience. We constantly communicate with our colleagues in our particular discipline through seminars, meetings, and particularly peer reviewed literature, which keeps us up to date with the research and developments in our discipline. At the best, our membership as practitioners of our discipline is based on a background and an interest which allows us to one degree or another to understand and assess and keep current with a particular base of community knowledge among other such qualified scientists. This allows us to be familiar with, interpret and apply the best current knowledge in a certain field and hopefully to gain the respect of the our colleagues in the scientific community. Our reputation for scholarship and integrity is paramount to our ability to function in such a community.
When we come to testify, we can’t just make up theories or conclusions on the spot because we may wish them to be true or say anything that we think would necessary to please somebody. We report to the judge and the jury our assessment of the current scientific community’s assessment of the problem, which we are qualified to do by years of training and years of thoughtful experience. There may be less dedicated or less well trained people who misunderstand and state wrong conclusions. There may be people biased by particular loyalties imposed by those that employ them: as an example, the tobacco apologists. There may be people asked to relate their opinions who do not have the proper background to support those opinions. But if a person is qualified, experienced and dedicated to professional standards, he can no more change his opinion to suit a particular side of the courtroom than a physician could avoid giving a patient a diagnosis of cancer. If I did so, I could be proven wrong by the literature in my own field. I would be useless to my profession and I would lose my self-respect and the respect of my honored friends and colleagues in my field. I am not going to do this for anyone. Therefore, I can only tell you or anyone the facts of my discipline and whichever side finds that scientific knowledge helps his case will call me as a witness. It would be odd if I did in fact testify for one side in a case on a recurring issue and then the other side the next time. My opinions do not change because of the needs of potential clients.
Think of it this way. I suppose I could choose to drive home from this courthouse on the wrong side of the road. I might get away with it for a block or even several, but eventually there would be a very bad car wreck. Such conduct makes no sense, and your suggestion that I might adapt my testimony to please someone is equally absurd.
 Kirby Riffel graduated from the University of Arkansas Fayetteville School of Law where he was president of the student body and law review. He practiced law in Memphis doing civil trial work for four years and moved to Pocahontas, Arkansas in 1971 where was admitted to the Arkansas bar and he has practiced in Pocahontas since that time. Mr. Riffel has completed the Datamaster technician’s course in Mansfield, Ohio at the factory. He has twice completed NHSTA Standardized Field Sobriety Student course, first in Cleveland Ohio in 1996 and then he sponsored such a program in Little Rock in 2008. He is a founding member of the National College for DWI defense and has attended many, many seminars sponsored by that organization over the last 15 years. Recently he has been a speaker at a DWI seminar in Cheyenne, Wyoming; West Memphis, Arkansas; Tunica, Mississippi; Columbus, Ohio; Little Rock, Arkansas and other places. He has organized and sponsored a two day seminar on the Intoximeter EC/IR breath machine in the spring of 2009 at Mt. Magazine attended by lawyers from all over the country. In 2010 he organized and presented a mock trial in Little Rock, Arkansas based upon a DWI case. Mr. Riffel has tried hundreds, if not thousands of DWI cases. Ninety percent of his practice involves defending persons accused of Driving while intoxicated. He has traveled to Ukraine on three occasions to be a visiting lecturer in various law schools throughout the country.