Malpractice

n. unethical or improper professional conduct, professional negligence, professional misconduct (Law); negligence, misconduct

v. commit malpractice, violate professional codes of conduct (Law)

In law, malpractice is a type of tort in which the misfeasance, malfeasance or nonfeasance of a professional, under a duty to act, fails to follow generally accepted professional standards, and that breach of duty is the proximate cause of injury to a plaintiff who suffers damages. It is committed by a professional or her/his subordinates or agents on behalf of a client or patient that causes damages to the client or patient. Perhaps the most publicized forms are medical malpractice and legal malpractice by medical practitioners and lawyers respectively, though malpractice suits against accountants (Arthur Andersen) and investment advisors (Merrill Lynch) have featured in the news more recently.
See more at Wikipedia.org...

Noun
1. professional wrongdoing that results in injury or damage; "the widow sued his surgeon for malpractice"
(hypernym) wrongdoing, wrongful conduct, misconduct, actus reus
2. a wrongful act that the actor had no right to do; improper professional conduct; "he charged them with electoral malpractices"
(hypernym) wrongdoing, wrongful conduct, misconduct, actus reus

(n.)
Evil practice; illegal or immoral conduct; practice contrary to established rules; specifically, the treatment of a case by a surgeon or physician in a manner which is contrary to accepted rules and productive of unfavorable results.
  

injurious conduct by an individual acting in an official or professional capacity, such as a doctor.