As you know, when a plaintiff sues a lawyer for malpractice in a litigation matter alleging that the defendant's representation caused the plaintiff to lose a claim, the plaintiff has to show that they would have won the case had it not been for the negligence of the defendant (the lawyer). In torts terms, this is what the plaintiff has to argue and prove in order to establish the element of cause in fact. Typically, however, courts hold that showing that the plaintiff would have won the original case (sometimes referred to as "the case within the case") is not enough because if the plaintiff would not have been able to recover anything in that case then the plaintiff can't establish an actual "loss" (the element of injury, in torts terms).
This means that typically, the plaintiff has to show not only that the plaintiff would have won the original case but for the negligence of the lawyer, but also that the plaintiff would have been able to collect the judgment (or at least part of it) as a result.
I am writing about this today because the Legal Profession blog reported a few days ago that the Louisiana Supreme Court recently decided a case that appears to be the first time a court has held that the plaintiff in a legal malpractice suit need not prove that the underlying lost judgment was collectible.
The case is called Ewing v. Westport Insurance and you can read it here.