By Nikolay Chsherbinin ( August 9, 2021, 8:34 AM EDT) -- In most jurisdictions, an expert witness is not permitted to give opinion evidence at trial unless the party has served a report signed by the expert, which includes the substance of the expert’s proposed testimony, and the expert has been qualified as such at trial. The rationale behind this principle is to avoid trial by ambush and to ensure the subject matter of the expert’s testimony is appropriate. The fees of experts to prepare reports vacillate as much as the seven seas and are not subject to reduction based on the traditional distinction between substantial and partial indemnity costs....