Medical malpractice is professional negligence by act or omission by a health care provider in which care provided deviates from accepted standards of practice in the medical community and causes injury or death to the patient. Standards and regulations for medical malpractice vary by country and jurisdiction within countries. Medical professionals are required to maintain professional liability insurance to offset the risk and costs of lawsuits based on medical malpractice.
A doctor would be liable for (depending on the circumstances) such things as prescribing experimental drugs and performing cosmetic surgery.