What BS. When you are contacted as an expert witness, you are specifically asked if you "think" you could find that _____. I guess you could end up with an adverse opinion, but the attorneys make it pretty clear what they are looking for, and everyone I know who is asked the question says "no" if they are pretty sure they won't come back with the "right" answer. You would rarely get asked again if you didn't operate that way.
Minor4th, is it discoverable if a consultant finds something adverse to the defense's case?