The study of ethics is an effort to understand and examine the moral life. The Hippocratic Oath is revered as one of the oldest codes of medical ethics. More recently, the American Medical Association Code of Ethics (earliest version in 1847) and the American College of Emergency Physicians Code of Ethics (1997 and 2008) have provided guidance to emergency physicians in the application of ethical principles to clinical practice. Most ethical codes share common tenets such as beneficence (doing good); nonmaleficence (primum non nocere, or "do no harm"); respect for patient autonomy, confidentiality, and honesty; distributive justice; and respect for the law. Ethical dilemmas arise when there is a potential conflict between two principles or values. Physicians resolve these dilemmas by gathering additional information; conducting meetings with other healthcare professionals, patients, and families; and applying an informed judgment in individual situations. In some circumstances, physicians may seek the involvement of the institutional ethics committee or the judicial system.