In the case of In Re Chaparrel Resources Inc. Shareholders Litigation, 2007 WL 2998967 (Del. Ch., Oct. 11, 2007), read opinion here, the Chancery Court provides instruction on the perils of using the same firm for both a non-testifying consultant and an expert who will testify at trial–without a clear dividing wall being established between the two persons (or teams) within that same firm.  This decision involved a motion to compel data from a non-testifying consultant.

At the heart of this issue in this opinion is an analysis of , and comparison of, Chancery Court Rule 26(b)(4)(A)(i) and Rule 26(b)(4)(B). Paraphrasing, subsection (b)(4)(A)(i) allows discovery of an expert who will be testifying at trial and the data on which he relies. However, subsection (b)(4)(B) does not allow discovery of a non-testifying consultant absent "exceptional circumstances",  which is a very high threshold that the defendants here who filed the motion to compel did not try to meet. In sum, the court here determined that because the testifying expert relied on the non-testifying consultant and the two worked together (in the same firm) on the final report used in the case, then the defendants were entitled to discovery concerning that non-testifying expert under subsection (b)(4)(A)(i)–not subsection (b)(4)(B).

Moral of the story: If one does not use two separate firms from which to hire both a non-testifying consultant and the testifying expert, one is playing with fire in terms of exposing the non-testifying consultant to discovery.