Legal malpractice puts you in a difficult position as a client. You're relying on your attorney to be educated and respectful of your needs. You hire an attorney to represent you and to look out for your best interests. If you find out that he or she is not doing that, then you could feel violated and angry.
Legal malpractice happens when an attorney doesn't perform duties in accordance with the typical standards and codes of professional or ethical conduct. That doesn't mean that you can file a claim against your attorney because a case doesn't work out in your favor, but it does mean that you may have a case if your attorney was negligent or caused you to lose your case for one reason or another.
Attorneys have a responsibility to provide you with skillful representation. If an attorney breaches that duty and causes you financial losses, then you can file a lawsuit against him or her for compensation. For instance, if the attorney misuses your funds, that is a breach of your client-attorney relationship. The same is true if the attorney has a conflict of interest in the case and has an interest in you losing the argument.
Simply being negligent is also possible in some instances. For example, if an attorney forgets to call you, file paperwork or show up for court, you could prove that he or she was in violation of a code of conduct or failed to uphold his or her duties. If you're successful, then your past attorney may be responsible for your losses and have to pay.
Source: FindLaw, "What is Legal Malpractice?," accessed Sep. 29, 2017