professional responsibility: an overview
The legal profession has existed for over two thousand years. From the Greek city-states and the Roman Empire to present day United States, legal advocates have played a vital and active role in the formulation and administration of laws. Because of their role in society and their close involvement in the administration of law, lawyers are subject to special standards, regulation, and liability. Sometimes called legal ethics, sometimes professional responsibility, the topic is perhaps most comprehensively described as the law governing lawyers.
Since lawyers are admitted to practice by states this topic is largely one of state law. However, as federal courts can and do set their own practice rules and federal agencies do as well, the topic has a federal component, too.
This area of law is covered extensively in the LII's American Legal Ethics Library which includes comprehensive links to primary sources for each U.S. jurisdiction and commentary on the law of lawyering for a growing number of them.