1. The lawyer made a mistake. Just as an automobile driver can be liable if he or she makes a mistake driving a car, a lawyer can be liable if he or she makes a mistake while representing a client. The lawyer does not have to be a bad person, have evil intentions, or have violated an ethical rule of the profession. It is enough that the lawyer erred. Of course, if a lawyer was motivated by animus or greed the situation is even worse for the lawyer.
2. The mistake must be one an ordinary lawyer would not make. The question the judge asks a jury in a legal malpractice case boils down to whether the lawyer acted as a lawyer of ordinary prudence. Some kinds of negligence (such as missing the statute of limitations) are so obvious that a layperson can understand it was a mistake. But in most legal malpractice cases, expert testimony from other lawyers is necessary to inform the jury what the ordinary prudent lawyer would have done. For this reason clients are often ill equipped to recognize and act on lawyer malpractice. Consultation with a knowledgeable attorney may be the only way that a client learns he or she has been the victim of legal malpractice.
3. The client suffered significant damage. In some areas of the law, violations of duty trigger monetary penalties that may be unrelated to the damages caused by the violation. That is not generally true of legal malpractice claims. A lawyer may do something that subjects him to discipline or even disbarment, yet not have caused damages compensable in a legal malpractice claim. Although an attorney may be subject to fee forfeiture in some cases, recovery of damages in legal malpractice cases requires damages to the client that would not have occurred if the lawyer had done his or her job correctly. One example of this occurs when a lawyer negligently fails to file a case before the statute of limitations expires. As a result the client does not get to try his case. Yet, to recover on a legal malpractice claim, the client must prove that he would have won the case if the lawyer would have filed it on time. For that reason, malpractice cases arising from lawyers mishandling litigation require trying a “case within a case.” The client must prove both that his lawyer was negligent and that the client would have won the case.
4. Exoneration in Criminal Cases. For policy reasons, Texas and a majority of other states do not allow legal malpractice cases against lawyers for doing a bad job defending criminal cases unless the defendant is ultimately exonerated.