I have now been working from time to time as an expert witness for over 11 years. I have worked on major intellectual property cases, forensics cases, and a few criminal cases. In that time, I have seen other expert witnesses make some significant errors. Without mentioning specific individuals, cases, or parties (for obvious reasons) I would like to share some real-world stories from the trenches. And, of course, I will mention what you should avoid (either as an expert, or when hiring one).
In an intellectual property case I worked on, one of the major issues was software written in Java. As I read the opposing experts report I was struck by a number of oddities. Now this particular person had a doctorate in computer science and had been a professor of computer science for many years. But as I read his analysis it was simply wrong on many facts. Based on this I suggested some questions that the attorney’s who hired me might ask him at deposition. Well, under oath he had to admit he had never written a single line of Java code, never even read a book on Java, and could not read the code the attorney placed in front of him.
This may seem unbelievable. But I have seen similar things on other cases, particularly in computer science. Some people think expertise in a general area, like computer science, means they are an expert in every aspect of computer science. Frankly expert consulting pays well. And large intellectual property cases can mean a lot of billable hours. One might be tempted to stretch into areas that are related to one’s expertise. But keep in mind Federal Rule 702, which states (at least in part) “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.” You should be an expert in that subject, one who has knowledge well beyond the average. Simply having a vague familiarity with the topic is inadequate. And never assume expertise in one subject, automatically means expertise in related topics.