I am not a lawyer. My career as a forensic chemist, however, placed me within the environment of the criminal justice system. For most of that stretch, I had the title of forensic chemist. The job involved identification of controlled substances (illegal drugs). Drug law enforcement is classified as a “victimless crime”, which is to say that, rarely if ever does a subject complain to law enforcement, “arrest that person! He sold me heroin!”. To prove that a crime took place, one needs testimony that the substance changing hands is, in fact, what is alleged. (Often, the buyer hasn’t a clue as to what was actually sold – Caveat Emptor).
An “expert witness” is someone who posesses knowledge or experience relevant to the matter at hand which is not likely to be posessed by the triers of fact (jurors or judges). Experts do not need advanced degrees or, for that matter, degrees at all, just knowledge of some matter under litigation. The judge qualifies the expert in each case. A good expert can teach and reach ordinary folks without boring them to death, or, worse, talking down to them. One of the most entertaining examples I have ever seen was the part in the movie “My Cousin Vinny”, in which the character played by Marisa Tomei rebutted testimony of an FBI expert. She was a mechanic who worked in a garage. Probably no education beyond high school. The “feeb” tossed around jargon and totally failed to connect with jurors.
For several years, I taught rookie chemists from state and local labs who attended a weeklong seminar in DEA’s Special Testing and Research Laboratory. One of the major issues these people confronted was fear of the courtroom. My message to them was that they held an advantage in knowing chemistry far better than the lawyers. Unlike “fact” witnesses, experts are allowed to explain findings well beyond yes or no.
In my own experiences, I discovered some anomalies. Although evidence of the identity of a substance had to be introduced, many experienced defense attorneys did not want expert testimony; they would ”stipulate” (admit to) lab findings. Much of trial proceedings involve drawn out, tedious, sleep inducing arguments over arcane issues. If an expert is introduced, a lot of stuff is clarified. Jurors are graphically reminded that we are dealing with a bad guy, a distributor of (say) heroin. In one of my first cases, I was cross examined at great length by an attorney who, it turned out, was court appointed. He was trying to assess the new kid on the block! I’m not sure he would have done this for a paying customer. (The judge asked me whether I was able to tell heroin apart from every substance in the world? Witness :Yes,your honor. Judge: He’s qualified). Another tactic, particularly if interstate travel was involved, was to require you to show up to testify, and stipulate, once you show up. Who knows, one might get lucky, the plane crashes….
One of my favorite trap questions involves whether a book, scientific paper, etc., is authoritative. If you answer “yes” (even if it’s one you wrote), you own every word, sentence, paragraph, typo, etc etc, in the entire tome. The only correct answer: Just.Say.No. A lot of stuff can readily be taken way out of context.
Obviously, there’s a great deal more involved (probably entire courses in law school) but it would be wise for would-be experts to remember:
It’s a game
It’s the world of illusion
I care. But Not. Too. Much.