Numerous Texas cases have held that the courts will not allow a plaintiff to "fracture" a legal malpractice claim into other causes of action--such as breach of contract or breach of fiduciary duty--where the allegations are solely that an attorney failed to use the degree of care, skill and diligence that attorneys of ordinary skill and knowledge commonly exercise. See, for instance, Goffney v. Robson, 56 S.W. 3d 186, at 190-194 (Tex. App.--Houston [14th Dist.] 2001, no pet) and the cases there cited.
This "defense" is not as potent as commonly claimed in the legal malpractice defense community. The statement in the previous paragraph is not remarkable because the sole cause of action actually alleged is what is clearly defined as legal malpractice. Breach of fiduciary duty, for instance, requires allegations that the attorney used his position of trust to benefit himself to the detriment of the client. In the statement of law made above, that allegation is not made.
That does not mean, however, that the same case may not legitimately involve claims of legal malpractice and other claims against the lawyer, such as breach of fiduciary duty, or perhaps fraud or DTPA. Rather, it means that the allegations and evidence have to prove those other causes of action, as well as legal malpractice. It is entirely possible, for instance, that a case could involve lawyer negligence--legal malpractice--and also lawyer self-dealing to the client's detriment--breach of fiduciary duty.
Nonetheless, there have been a number of cases where nothing aside from negligence was alleged, and yet the plaintiff attempted to tack on other causes of action. That is the "fracturing" which is forbidden. Why would a plaintiff do that? It usually involves a statute of limitations issue. The statute of limitations for legal malpractice is two years; but for breach of fiduciary duty or breach of contract, it is four years. These cases usually have a limitations issue with regard to the malpractice claim, and the plaintiff is trying to wiggle out of it by using labels of claims with four year statutes.
Nonetheless, in some circles, a misunderstanding has arisen that if a case is one for legal malpractice, it is not possible for any other cause of action to be pleaded or proven in that case. That is clearly not the law. Rather, a case with the right facts for multiple causes of action can validly go to judgment on the multiple claims.