Expert Witnesses

I’ve always wondered how the two sides in a trial or lawsuit manage to get expert witnesses to testify exactly the way they want. I can think of three possibilities.

  1. The experts know what is expected of them and try to find ways to tailor the facts and their judgements to produce the desired effects. If this is true then the experts are little more than lawyers, and I would think the jury should be appraised of this fact.

  2. Certain experts are known to hold opinions beneficial to one side or the other, and the lawyers seek out those who they know to hold favorable opinions to their case. This can easily be the case with the likes of insanity defences, but I’m not sure if it is alweays possible.

  3. The lawyers keep consulting experts until they get one who says what they want to hear.

Maybe some combination of all three factors is the answer, or something else that I’ve overlooked. Perhaps someone familiar with the legal system can help out with this.

Not everyone can be an expert.

Before a witness may testify as an expert, the side offering his testimony must qualify him as an expert, by asking questions designed to show the witness’ expertise - years of experience, training, number of scholarly articles published, and the like.

An expert witness is permitted to offer his opinion on what a certain set of facts implies. This is different from a lay witness, who typically may only testify to what he saw or heard himself. The rationale behind this rule is that the trier of fact - the jury, usually - brings to the fore their own ordinary, common life experience, which they may use to draw reasonable inferences from the facts. But when interpreting the facts requires special expertise, such as DNA, blood splatter analysis, or psychological infirmities, an expert witness can help the fact-finder by offering his interpretations of what the facts imply.

Some fields of endeavor do not lend themselves to different, yet still credible, interpretation, and others do. Two DNA experts may differ as to how to compute probabilities of different people matching a particular specimen, but they would be quibbling over one in a million as opposed to one in ten billion. DNA analysis has certain accepted criteria, and there’s not a useful amount of wiggle room. No matter how much a defense lawyer offers to pay, or how far he searches, he won’t find a credible expert to impeach DNA evidence analysis. (Accusing the police of planting the evidence, of course, might be viable).

But the standard for insanity is a little different. It depends solely on the judgement of the examining psychiartist - did the accused suffer from a mental disease or defect such that, at the time of the act, he was unable to distinguish right from wrong? There’s nothing to weigh or measure here; the expert must simply offer his educated guess. Obviously, certain experts are predisposed to believe that anyone who commits a heinous act likely cannot tell the difference between right and wrong, while others are equally predisposed to believe that it takes a lot to overcome the presumption that all people know right from wrong.

Experts being human, undoubtedly some are swayed in their opinion by the knowledge that they won’t get paid by the defense if they conclude that the accused was sane.

In the end, each of the three possibilities you post has something to do with it. The idea, I think, is that the stronger that facts are, the easier it will be to find an expert whose conclusion is “right” – and the more convincing that expert will be to the jury.

The reality is that money helps - a lot.

  • Rick

Well the OJ routine was to claim that the blood was all contaminated. They had their expert (Dr. Henry Lee) up testifying to this. But other experts may disagree on the chances and impact of potential contamination.

I would add this:

  1. The expert makes their opinion known to the police and attorneys in the case from the very beginning.

My mom is a pediatric radiologist, and is often the first person to know outside the family that child abuse is occurring (e.g. she can tell if the type of fracture the child has doesn’t match the explanation given for the injury). She has reported such crimes to the police and has served as an expert witness in several trials of child abuse cases. She also had a small part in a PSA on child abuse years ago.

I might point out that, in effect, all three of the reasons included in the OP are what result in ‘expert’ testimony supporting almost any theory. Having spent years dealing with so-called ‘expert’ testimony from various MD’s, OD’s, DO’s and DC’s (to say nothing of the PhD’s in psychology) in workers’ compensation cases in California, I can assure you that, given sufficient numbers of ‘experts’ in a field, you will eventually find one which either a)Truly believes that white is awfully close to black, or b) is willing to SAY white looks a lot like black under the circumstances of the case.

Credibility of an ‘expert’ witness is often the key issue in such cases. It becomes the job of the attorney for the other side to establish, through careful cross-examination, and through proper use of his/her own ‘expert’ witness(es) that the opinion(s) proffered by the other side are just so much doggy doo doo.

I can see that with DNA it might be hard to refute some of that evidence, but my best friend is a biomechanical engineer and EMT in addition to an expert witness in lower speed auto accidents and has testified both for and against insurance companies denying injury claims. Truth is, depending on how your body or head is turned, or other extreneous factors in the vehicle itself at the time of impact, a 25-30mph collision can be one you walk away from without a scratch or it can kill you.

Admittedly, however, there is some truth to what you say about reputation. About 90-95% of the cases he does are for the defense (i.e. the insurance company) and he does believe that with very few exceptions, people he has dealt with are trying to defraud the insurance company which ultimately hurts us all in higher rates. He has also passed on cases, or recommended that they settle out of court where he is less sure.

He is often, for example put in the position where he has to determine if injuries in an accident are the result of a pre-existing condition, and the accident only agrravated it. At an extreme, this was a woman who previously had polio as a child, saw a chiropracter regularly, and thought it might be nice if her klunker could conveniently get rear-ended to have the insurance company pay her ongoing bills. On the other hand, sometimes very old drivers get in accidents that cause what might be termed unusual injuries for a normal person but wrecks hell on an old person’s feeble body. When that is the case, he will not lie for the insurance company. In fact, they pay him to review the case and write the report WHATEVER he says, and only pay him additional monies if he has to testify. And believe me, he would prefer not to as he hates lawyers. Fortunately, he seems to hate chiropracters more…