What showing is required in order to prevail on a legal malpractice claim resulting from a personal injury action?

"A plaintiff must demonstrate that he or she would have succeeded on the merits of the underlying action but for the attorney's negligence," according to the First Department in Aquino v. Kuczinski, Vila & Associates, P.C., decided on April 3, 2007. The court noted that it is a difficult showing since, in effect, it requires the proving of a case within a case, both of which require that proximate causation be established.