malpractitioner

/ˌmælprækˈtɪʃənər/
noun
  1. A professional (such as a doctor or lawyer) who fails to perform their duties properly, often causing harm or loss to a client or patient.
    • The lawyer was labeled a malpractitioner for mishandling several client cases.
    • The hospital fired the malpractitioner after the investigation found serious errors in patient care.
    • A malpractitioner can lose their license to practice if found guilty of negligence.