For a number of reasons, including skyrocketing expert witness costs, courts, arbitration panels, and disputing parties may decide to jointly retain a single "neutral" expert witness to represent both opposing parties in litigation or arbitration proceedings. Parties may also desire to jointly hire an expert to narrow the disputes, shorten the proceedings, reduce the costs, and have fewer post-decision protests. However, the parties' desires can be hindered if they do not consider certain practical implications before jointly engaging an expert witness. Here are a few practical matters to ponder:
Contracting
Who are the clients? In fact, there are at least three parties who must agree to the use of a jointly retained expert—each of the disputing parties and the trier of fact (the judge or the arbitrators). For this reason, all parties must agree on the contracting mechanism (a court order, engagement letter, or combination of both). By rule, formal litigation will certainly include a judge's order of employment, which ensures that the expert witness has immunity from liability.
Who makes the calls? Although it is commonplace for the disputing parties to agree to split the expert's fees and expenses (see Cost Sharing below), there is disparity in practice regarding who has the final say to direct the expert work and deliverables. Needless to say, in formal litigation the judge always reserves this right.