In federal court, effective 1 December 2010,  Federal Civil Rule 26 prevents discovery of most conversations and communications that experts and attorneys have in working together as the expert's report is developed, evidentiary themes developed and strengthened , and oral opinion testimony perfected. Although it is expected that the states will follow with similar amendments to their discovery rules, not all states have done so – yet.

What is the Federal Rule, as of 1 December 2010?

The present (as of December 2010) Federal Rule returns the primacy of the attorney work-product protection. The Rule says (A) the expert's draft reports and (B) other expert-attorney communications are not discoverable, with three exceptions. Those three exceptions on "other communications" between expert and attorney are communications that:

 The Committee Note, by the Supreme Court Advisory Committee, stresses the following:

• The "refocus of disclosure on ‘facts or data’ is meant to limit the disclosure requirement to material of a factual nature, as opposed to theories or mental impressions of counsel."
   
• The exception to allow discovery of the identity of "facts or data [supplied by counsel] for the expert witness to consider in forming expert opinions":

"is limited to those facts or data that bear on the opinions the expert will be expressing, not all facts or data that may have been discussed by the expert and counsel," and
 

is limited to "identifying" the facts or data" — "further communications about the potential relevance of the facts or data are protected."
 

does not include "assumptions" furnished by counsel. Assumptions are distinct from facts and data. Assumptions are discoverable only if they are actually "relied upon" by the expert in forming the opinion.

As stated earlier, the Federal Rule 26 (as of 1 December 2010) exempts from discovery an expert’s draft reports. The Rule adds: "regardless of the form of the draft."  According to the official Committee Note, that phrase is designed to afford protection to all drafts, "oral, written, electronic or otherwise." The concept of an "oral" "draft" presumably encompasses conversations relating to a required written Rule 26(a)(2)(B) report.

Federal protection extends to non-reporting experts.

The Rules require experts "retained or specially employed to provide expert testimony in the case or one whose duties as the party’s employee regularly involve giving expert testimony." to submit written reports which are to be disclosed to the adverse party. But no report is required (even though disclosure from the party may be required of the subject matter, facts, and opinions to which the witness is expected to testify.) of other experts in the case.  For example, a treating physician, an employee whose duties do not regularly involve giving expert testimony, or a third party witness don't have to furnish a report.  The revised Federal Rules also protect the expert-attorney conferences and communications. However, because of the separation in the Civil Rules of the duties and extent of discovery regarding experts into separate rules for "report required" and "no report required" witnesses, you have to look at both Rule 26(b)(4)(C) and 26(a)(2)(B) for the protection now afforded for expert-attorney communications.

A form set of additional paragraphs to power your next
subpoena duces tecum of an expert,
whether in federal or state court, is available

In state court, consider stipulating to limit discovery of communications between attorney and expert to those discoverable under the federal Rule 26 as it is after 1 December 2010.

Our form for a subpoena duces tecum for an expert deposition asks you to consider whether the jurisdiction involved has a definite rule on the subject of expert-attorney communications.  Based on your conclusions, you can use one of two alternatives for whether your subpoena duces tecum will demand attorney-expert communications to be disclosed.)

Most state courts interpret the former Federal Civil Rule 26(a)(2)(B) (and the similar state rules) to mandate disclosure of everything communicated between counsel and his/her testifying expert -- including the attorney’s strategy or other items that would be otherwise protected by the rules for protection of attorney’s mental work product. The express words of the rule regarding expert discovery  were held to create a mandate of discovery which trumped the protection of attorney work-product or privilege. Put another way, most courts (both federal and state) held that an attorney's disclosure of work product to a testifying expert waived the work product privilege. See, e.g., Regal Airport Auth. v. L.G., LLC, 460 F.3d 697, 716 (6th Cir. 2006); and Gall ex rel. Gall v. Jamison, 44 P. 3d 233 (Colo. 2002).

The jurisdiction of the lawsuit may have law that answers the question as you want it answered. If the jurisdiction does not answer the question for you, or you don’t like the jurisdiction’s answer, you can make a reciprocal agreement with the adverse party. You might want to agree with your state court adversary to limit  discovery of communications between attorney and expert to those discoverable under the federal Rule 26 as it is after 1 December 2010. Notice I said "reciprocal." If you don’t make a reciprocal agreement, you may find that at a later deposition of your expert the adverse attorney is demanding production of more than you demanded from their expert.  What you demand that their expert produce at your deposition of their expert will be the minimum (not the maximum) that your adversary will demand that your expert produce. So – if you don’t want to follow the rule of your jurisdiction – make your agreement with the other attorney on the subject of attorney-expert communications a reciprocal agreement - in writing.