In a legal malpractice case, the plaintiff usually presents an expert to support the allegation that the acts and omissions of the defendant lawyer were below the standard of care and negligent. In addition, any experts that would have been appropriate to present in the underlying case are usually fair game. For instance, where the underlying matter was a personal injury case arising out of an auto accident, and the matter was dismissed before trial due to the lawyer's negligence, an accident reconstruction expert might be presented to explain how the collision occurred, and a medical doctor might be presented to support the nature and extent of the plaintiff's injuries. Opposing defense experts would also likely testify in these areas.
A common defense trick is to attempt to present a lawyer expert to testify that the underlying case was a bad case for an assortment of reasons, and thus could not have been won, and thus the jury in the malpractice case should award no damages. In most cases this is completely out-of-bounds and should be anticipated and opposed. Assume for example that the underlying case was for medical malpractice, and that the case never went to trial because the lawyer negligently failed to compute the time limitations for bringing suit. Assume further that the legal malpractice case identified as malpractice the failure to file suit within the statute of limitations or to obtain informed client consent not to so file.
The plaintiff can present evidence that the lawyer undertook to file the case, that it was not timely filed, and that the client never provided informed consent to abstain from initiating a lawsuit. The defendant can present evidence disputing that the lawyer did not get informed consent, for instance. In addition, the plaintiff may call a medical malpractice lawyer as an expert to explain how the actions of the defendant lawyer in failing to obtain client consent not to file the lawsuit were below the standard of care, though in this example such testimony would be almost pro-forma, since the time limitations and the need for informed consent usually cannot genuinely be disputed.
Regarding the underlying case-within-a-case, the parties may also present whatever evidence might appropriately have been offered in the underlying medical malpractice case, such as medical experts, in support of conflicting positions that there was or was not medical malpractice, that the alleged medical malpractice was or was not the cause of the plaintiff's injuries, and to opine regarding the scope and extent of any claimed injuries.
However, what the defense cannot do is present a medical malpractice lawyer expert to opine that the underlying medical malpractice case was no good. Legal Malpractice, Mallen & Smith, 2008 Ed., 34.20, pg1173; Brust v. Newton, 70 Wash.App. 286, 852, P.2d 1092 (1993).
The case-within-a-case represents the causation and damages portion of the legal malpractice trial. Determination of damages is exclusively the province of the jury. The malpractice jury acts as a stand-in for the would-be jury in the underlying case, and decides the underlying case just as a jury would have if it were presented in the first instance. In a straight medical malpractice case, the parties may testify, and doctor experts may opine, regarding treatment, standard of care, and injuries. The lawyers for the parties may present opening statements and closing arguments in which they vouch for or disparage the other side's case, but under no circumstances are the parties allowed to put on lawyer experts in the medical malpractice case to testify that, based on years of experience handling medical malpractice cases, the medical malpractice case being heard by the jury is really good, or really bad, and thus the jury should find for one or the other party, and award lots of damages, or no damages. Likewise, this would be highly improper (indeed, reversible error) as a means of presenting the medical malpractice case-within-a-case in the legal malpractice trial.
Plaintiff's counsel should be cognizant of how and when the plaintiff could be opening the door to this kind of testimony, however. A medical malpractice attorney's appraisal of the merits of the underlying medical malpractice case-within-case could be fair game if the plaintiff makes it a liability issue. Suppose in the above example the plaintiff alleges in the malpractice complaint that the defendant lawyer, in addition to failing to file with the statute of limitations and failing to obtain client consent, also listed an inappropriately low figure for the client's damages in a pre-suit tort claims act notice to the opposing side, potentially limiting the amount recoverable in the lawsuit that was never brought. That could open the door for the defense expert lawyer to speak to the value of the underlying case, not (ostensibly) to condition the jury’s views about to damages per se, but in order to rebut the argument that the defendant lawyer committed malpractice by undervaluing the case. Similarly, adding claims relating to lost settlement opportunities can open the door to defense expert testimony regarding the merits or de-merits of the underlying case.