Suppose, though, the expert for one party currently is on retention in another matter by the other party: plaintiff's expert is working for the defendant, but in some other unrelated case. The defendant's lawyer may fee constrained to cross-examine an expert who will presumably be testifying in that other case on his client’s behalf.
Nonetheless, in Atlantic City Associates, LLC v. Carter & Burgess Consultants, Inc., 2007 WL 63992 (D. N.J. Jan. 5, 2007), the court applied the two-part test (was there a confidential relationship; were confidences disclosed) and refused to disqualify the experts. It did not view the fact that the experts were currently retained by the client in another matter as a “decisive factor” but instead denied the motion to disqualify because there was no proof of a confidential relationship.
I hadn't seen one quite like that, and am sure I don't agree with the analysis, let alone the result.