The US malpractice system is based on tort law, which holds physicians responsible for not harming patients intentionally or through negligence. Malpractice claims are brought against physicians from most medical disciplines in proportion to their numbers in practice and to the frequency with which they perform procedures. Claims against chest physicians most commonly allege injuries caused by the following: (1) errors in diagnosis, (2) improper performance of procedures, (3) failure to supervise or monitor care, (4) medication errors, and (5) failure to recognize the complications of treatment. Most of these injuries occur in hospitals, and many of the injured patients die. The social goals of the medical malpractice system include the following: (1) compensating patients injured through negligence, (2) exacting corrective justice, and (3) deterring unsafe practices by creating an economic incentive to take greater precautions. Some patients injured through negligence are compensated, but most are not. Claims are brought against some negligent physicians but also some who are not negligent, and being negligent does not guarantee that a claim will be brought. The deterrent effect of medical malpractice is unproven, and the malpractice system may prompt defensive medicine and increase health-care costs. And by stressing individual accountability, it conflicts with a systems-oriented approach to reducing medical errors.