Professional malpractice is an act or continuing conduct of a professional which does not meet the standard of professional competence and results in provable damages to their client or patient. Such an error or omission may be through negligence, ignorance (when the professional should have known), or intentional wrongdoing.
Except in cases of extremely obvious or intentional wrongs, in order to prove malpractice there must be testimony of an expert as to the acceptable standard of care applied to the specific act or conduct which is claimed to be malpractice and testimony of the expert that the professional did not meet that standard. The defendant then can produce his/her own expert to counter that testimony.
Professions which are subject to lawsuits based on claims of malpractice include lawyers, physicians, dentists, hospitals, accountants, architects, engineers and real estate brokers.