There is little doubt that severe distortions are present in the legal adjudication of professional medical liability. The medical expert witness plays an important, often crucial, role in the medical liability cases. The expert assesses medical information, interprets and explains medical uncertainty, medical research, and customary practice for a nonscientific jury, and offers an expert level opinion as to whether the standard of medical care was met. When expert witnesses not merely disagree, but misrepresent data, misrepresent their background credentials and expertise, and offer egregiously false testimony, the legal process is violated and verdicts may be distorted. Many medical and surgical professional organizations, including the American Medical Association, have adopted programs that provide guidelines for members who serve as medical expert witnesses in professional liability cases. The American Association of Neurological Surgeons (AANS) was the first to develop a program to deal with irresponsible expert witness testimony. That program involves a published code of conduct, which outlines the expectations of society regarding expert witness testimony, and potential consequences for noncompliance. To date, the AANS program has withstood court challenge, in fact, has received judicial praise. Other medical societies, including the American College of Gastroenterology (ACG), have reviewed efforts by others and are considering developing their own programs.