This case illustrates an important difference in the law. In Pennsylvania, a party cannot sue for legal malpractice if that same party settled the underlying case, unless that party can prove that it was fraudulently induced into entering the settlement agreement.
In Kachmar, the plaintiff sued his former matrimonial lawyer on the ground that the lawyer failed to include a waiver of spousal support in a prenuptial agreement. Unfortunately, Kachmar settled the underlying divorce case, which meant that he could not bring a legal malpractice case.
Illinois does not follow this rule. In Illinois, a party which has settled the underlying case can sue for legal malpractice. Where a case is settled, it is often difficult to prove that but for the lawyer’s negligence, the party could have obtained a better result.
Source: Kachmar v. Litvin, Pa: Superior Court 2016 – Google Scholar