Page 24 - Expert Witness

cation of the expert witness, limitations on the expert testimony that can be given at the trial, or, in se-
vere cases, the exclusion of the expert witness testimony.

Generally, the practitioner will be allowed to testify at the trial if the expert witness’s opinions are based
upon sufficient facts or data and are the product of reliable principles and methods and if the expert wit-
ness has reliably applied the principles and methods to the facts of the case. However, the expert witness
typically is allowed to rely on hearsay as part of the basis for his or her opinions, a right not afforded
fact and lay witnesses. According to Rule 703 of the Federal Rules of Evidence,

[a]n expert may base an opinion on facts or data in the case that the expert has been made aware
of or personally observed. If experts in the particular field would reasonably rely on those kinds
of acts or data in forming an opinion on the subject, they need not be admissible for the opinion
to be admitted. But if the facts or data would otherwise be inadmissible, the proponent of the
opinion may disclose them to the jury only if their probative value in helping the jury evaluate
the opinion substantially outweighs their prejudicial effect.

In addition, case precedent has given the trial judge gatekeeping responsibilities and discretion related to
the admissibility of expert witness testimony (see appendix G, "Daubert and Kumho Case Summaries").
Therefore, it is possible that the practitioner’s expert report and associated opinions will be challenged
by the opposing legal counsel in an effort to exclude the practitioner’s testimony. This may be accom-
plished by filing a Daubert motion. Some reasons for the exclusion of expert witness testimony are that
the testimony

 is based on legal theories or remedies unavailable in the jurisdiction.

 fails to consider alternative scenarios, explanations, facts, and assumptions.

 fails to use procedures typically employed by similar professionals.

 ignores or fails to consider material facts and evidence in the case.

 employs unreasonable or unjustified use of a proven theory or technique.

 offers unreliable results.

 offers unsupported assumptions.

 uses unproven or generally unaccepted theories, methods, and techniques.

 uses untested, biased, or inadmissible evidence.

The practitioner engaged as an expert witness by the party initiating a civil complaint, referred to as the
plaintiff, generally submits his or her expert witness report first, although simultaneous submission by
the disputing parties is common. The practitioner engaged by the party subject to the complaint of the
plaintiff, or the defendant, submits his or her expert witness report afterwards, and it is often referred to
as a rebuttal report because it contradicts the plaintiff’s expert witness report. In some cases, additional
responsive or supplemental expert witness reports may be prepared and submitted by the practitioner. It
is important that the practitioner disclose the expert witness opinions prior to the closure of discovery
because failure to do so may prohibit the expert witness from testifying about these opinions at the trial.

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