In federal courts, if a party withdraws an expert witness is the expert’s deposition testimony still admissible over hearsay objections as an admission of a party-opponent? Maybe.
I haven’t really had much reason to explore this question. But, at least as of 2005, “[c]ourts are divided with respect to whether it is appropriate to treat expert deposition testimony — and specifically deposition testimony of a withdrawn expert — as an ‘admission of a party-opponent’ under Rule 801(d)(2)(C) of the Federal Rules of Evidence and therefore as an exception to the hearsay rules.” One court suggested a semi-middle ground.
When an expert is put forward as a testifying expert at the beginning of trial, the prior deposition testimony of that expert in the same case is an admission against the party that retained him. Where an expert witness is withdrawn prior to trial, however, the prior deposition testimony of that witness may not be used. That deposition testimony is hearsay.
This concept could create interesting pre-trial strategies where perhaps an expert’s opinions are not as strong as originally hoped.
 Minebea Co. v. Papst, No. 97-0590, 2005 U.S. Dist. LEXIS 49047, 2005 WL 6271045 (D. D.C. August 2, 2005).
 Glendale Federal Bank, FSB v. United States, 39 Fed. Cl. 422, 425 (Ct. Cl. 1997).