Cooper v. Schoffstall No. 212 MAP 2004 (September 7, 2006)
Holding: Pa.R.Civ.P. 4003.5 restricts the scope of all discovery from non-party witnesses retained as experts in trial preparation. The threshold showing to establish cause for supplemental discovery intended to show favoritism by a non- party expert witness is of reasonable grounds to believe that the witness may have entered the professional witness category. Proponents of such discovery should demonstrate a significant pattern of compensation that would support a reasonable inference that the witness might color, shade, or slan this or her testimony in light of the substantial financial incentives. The appropriate entry point, upon a showing of cause, is a deposition by written interrogatory under Pa.R.Civ.P. 4004. The Court declines, however, to foreclose the trial court, after an assessment of interrogatory responses and upon appropriate motion, from determining whether there is cause to support further supplemental discovery.