In the United States
In the U.S., each state or territory has a code of professional conduct dictating rules of ethics. These may be adopted by the respective state legislatures and/or judicial systems. The American Bar Association has promulgated the Model Rules of Professional Conduct which, while formally only a recommendation by a private body, have been influential in many jurisdictions. The Model Rules address many topics which are found in state ethics rules, including the client-lawyer relationship, duties of a lawyer as advocate in adversary proceedings, dealings with persons other than clients, law firms and associations, public service, advertising, and maintaining the integrity of the profession. Respect of client confidences, candor toward the tribunal, truthfulness in statements to others, and professional independence are some of the defining features of legal ethics.
The Multistate Professional Responsibility Examination (MPRE) is used to measure examinees' knowledge and understanding of established standards related to the professional conduct of lawyers. The MPRE is a prerequisite or corequisite to the bar examination for admission as an attorney at law in 48 of the 50 states of the United States, as well as the District of Columbia, Guam, the Northern Mariana Islands, the U.S. Virgin Islands, and the Republic of Palau. Of the 56 jurisdictions within the United States, only Maryland, Puerto Rico, and Wisconsin do not use the MPRE; however, these jurisdictions still incorporate local ethics rules in their respective bar examinations.
Maynard Pirsig, published one of the first course books on legal ethics, Cases and Materials on Legal Ethics, 1949. Maynard Pirsig also published the definition of Legal Ethics, in Encyclopedia Britannica, 1974.
Some U.S. states, including New York, require applicants seeking to become attorneys to have taken a course in professional responsibility during law school.