Expert witness testimony can go beyond the contents of an expert report as long as the conclusions are consistent with the report and don't add any new theories that would unfairly "surprise" the other side, a federal judge has ruled.href="#">1
Some attorneys prefer that the expert not prepare a report if the venue so permits - because they are concerned with "boxing in" the expert's opinions. While federal courts and some state courts require expert reports, many state courts and most county and city courts do not, and no administrative agencies that I am aware of require expert reports (for example, a state department of motor vehicles that hears manufacturer-dealer disputes).
When preparing an expert report, however, either because one is required or because the attorney wants one, I try to make some statements general enough that they can be expanded, if need be. Most assertions in an expert report must, of course, be very specific - e.g. statements pertaining to a dealer's market penetration.
I prefer to have a report if my opinions are numerous, or contain significant detail that would be hard to recite without the report in front of me. On the other hand, I have had success in recent depositions with using (1) a CV and spreadsheets only, and (2) a CV and a simple bulleted list of points listing my opinions. I used the first in a deposition for a case involving the value of allegedly damaged automotive parts. Three spreadsheets listed the alleged damages as the plaintiff listed them; sorting the parts by quantity; and a third expressing my opinions, line by line, on the values of the items.
This technique worked well. The examiner in the deposition, once he went through my CV, had the spreadsheets, but no written opinions, with which to examine me. Using the spreadsheets, I was able to describe the reasoning behind my opinions - how I adjusted the plaintiff's values.
The case with the bulleted list involved a dealer termination, and covered such topics as dealer market share, working capital, profit and loss, investment in facilities, and sales efforts. This document, once marked as a deposition exhibit, comprised a complete list of the opinions I intended to express at the trial of the matter. In my deposition testimony, I made sure that I incorporated this list into my answer to the question, "Do you have any other opinions?" My answer was, "If there is anything on the bulleted list that we haven't covered, let me make it clear for the record that any such topic is, in fact, part of my opinion."