Should you hire multiple experts on the same topic? There are some very good reasons to use this strategy.
If the case justifies the expense, retaining multiple consultants in the same field has a variety of advantages. You can:
Have the consultants “compete” and then designate the stronger as a witness to testify at trial;
Place primary reliance on the stronger consultant, but designate both as trial witnesses, keeping the other in reserve in case a particular issue needs corroboration;
Designate one as the eventual expert witness, keeping the other purely as a consultant in whom you can confide fully and use as a “guinea pig” for testing untried theories; or
Have the different witnesses pursue entirely different theories and approaches and wait until the formal CCP §§2034.010-2034.730 disclosure time to choose the expert who will make the stronger, more persuasive witness.
If you use multiple experts in the same field, keep them apart as much as possible. Ideally, each expert shouldn’t even know that any others are on the case. If this is impossible, tell each to avoid contact with the others about the case. Only by maintaining such separateness can you ensure that one expert won’t “contaminate” the other.
When the number of qualified experts is extremely limited (or at least the number available locally is extremely limited), some attorneys contact and retain every available expert, not with the intent of using them all, but to keep them from working for the opposition.
Be mindful that, although the number of experts a party can retain is unlimited, the court does have the power to limit the number of experts that a party can call at trial. Evid C §723. To date, no reported case has dealt with exercise of this power before trial, but several cases have affirmed the court’s limitation of the number of experts a party may call at trial when testimony on a subject has become cumulative. See, e.g., South Bay Chevrolet v General Motors Acceptance Corp. (1999) 72 CA4th 861, 85 CR2d 301.