All I can say is that I didn’t make a penny, and that O.J. is now where he belongs.
I worked on many DNA-based cases in the 1990s; my expertise involved making sure that the prosecution used DNA evidence properly in its population-genetic calculations. The state often got the calculations—the “match probabilities”— completely wrong, biasing the data against the defendant. (A “match probability” must be calculated when the defendant’s DNA matches other DNA-based forensic evidence, like blood or semen at the crime scene. It involves comparing the defendant’s genotype with that of a “random” sample of the population, calculating the probability that the defendant-forensic match could have occurred just by chance. This involves principles that are common in evolutionary genetics.)
I ensured that these calculations were correct and, if I had to, took the stand to explain to judges and juries how match probabilities should be calculated. Try telling a jury of regular people, who barely know what DNA is, how to calculate Hardy-Weinberg equilibrium! That was a tough job.
My philosophy here was to make sure that my field was not corrupted by zealous prosecutors trying to secure convictions based on faulty calculations. Everyone deserves a fair trial, even rich and odious people like O.J. Almost all the cases I worked on, however, involved poor defendants who could not afford lawyers, and were represented by public defenders who were completely baffled by statistics. I took money in only the first case I dealt with, here in Illinois, and then decided that my testimony would look less “tainted” were I to work for free. So I did. But that tactic, of course, was also attacked by prosecutors: they would ask me, when I was on the stand, “Why aren‘t you taking money, Dr. Coyne? Are you on some kind of crusade or something?”
I have always thought that the hardest thing I’ve had to do in my professional life was to get on the stand in a murder trial, trying to deal with prosecutors who were more interested in convictions than truth, and who were determined to destroy my testimony any way they could. It’s nerve-wracking, for you know that somebody’s life is at stake. Next to that, a big symposium talk or a grant proposal is a piece of cake! Fortunately, I didn’t have to testify in the O.J. case.
People ask me how I could work for O.J., who seemed pretty obviously guilty. My answer is that I wasn’t concerned with his innocence or guilt, but with whether DNA data were presented properly to the jury. And of course everyone, rich or poor, deserves that kind of expertise. I worked for free on that case, too, though I could have made a pile.
Have pity on the poor defendants who can’t afford experts! One thing you quickly learn from this kind of experience is that there is different “justice” for the rich and poor.