Hillworth v. Smith
In Hillworth v. Smith, 425 Pa. Super. 17, 624 A.2d 122 (Pa. 1993), the Superior Court of Pennsylvania recognized the importance of avoiding the "prejudicial effect to both the insured and insurer which may result from disclosing the insurer's interest in the claim." 624 A.2d at 124.
Based on its interpretation of the Pennsylvania Rules of Procedure, that court determined that a subrogated insurer did not have to be joined in an action brought by its insured.