Question: What is the requirement for causation in a legal malpractice case?

In essence, a legal malpractice action … requires the plaintiff to prove that he had a viable cause of action against the party he wished to sue in the underlying case and that the attorney hired was negligent in prosecuting or defending the underlying case (often referred to as proving a “case within a case”). See Kituskie v. Corbman, 714 A.2d 1027, 1030 (Pa. 1998) (citing Rizzo v. Haines, 555 A.2d 58 (Pa 1989)).

In proving causation, the legal malpractice plaintiff (former client of defendant attorney) must prove by a preponderance of the evidence the underlying case, and but for the defendant attorney’s neglect the underlying case would have resulted in a favorable judgment.