The court has discretion in the manner in which it determines the motion. While depositions of expert witnesses and evidentiary hearings are available to the court for this purpose, they should be utilized in limited circumstances. See the limitations set forth in Rule 4003.5 governing discovery of expert testimony.
In deciding whether to address prior to trial the admissibility of the testimony of an expert witness, the following factors are among those which the court should consider: the dispositive nature or significance of the issue to the case, the complexity of the issue involved in the testimony of the expert witness, the degree of novelty of the proposed evidence, the complexity of the case, the anticipated length of trial, the potential for delay of trial, and the feasibility of the court evaluating the expert witness’ testimony when offered at trial.
When a ruling on a pre-trial motion to exclude the testimony of an expert witness is deferred until trial, the trial judge may choose to decide the motion (1) before the expert witness testifies on the basis of evidence offered outside the presence of the jury or (2) after the expert witness testifies on the basis of testimony offered at trial, in which event the trial judge will strike the testimony of the expert witness if it is found to be inadmissible under Pa.R.E. 702 or 703. However, hearings on preliminary matters must be conducted outside the presence of the jury ”when the interests of justice require.” See Pa.R.E. 104.
231 Pa. Code ยง 207.1