Individual Restatement volumes are essentially compilations of case law, which are common law judge-made doctrines that develop gradually over time because of the principle of stare decisis. Although Restatements of the Law are not binding authority in and of themselves, they are highly persuasive because they are formulated over several years with extensive input from law professors, practicing attorneys, and judges. They are meant to reflect the consensus of the American legal community as to what the law is, and, in some cases, what it should become. As Harvard Law School describes the Restatements of the Law:
Each Restatement section includes a black letter principle, Comments and Illustrations, and, in the form of Reporters' Notes, a detailed discussion of all the cases that went into the principle summarized in that one section. By citing a Restatement section in a legal brief, a lawyer may bring to the attention of a judge a carefully studied summary of court action on almost any common law legal doctrine. The judge can then consider the Restatement section and make an informed decision as to how to apply it in the case at hand. While courts are under no formal obligation to adopt Restatement sections as the law, they often do because such sections accurately restate the already-established law in that jurisdiction, or on issues of first impression, and are persuasive in terms of demonstrating the current trend that other jurisdictions are following.
Restatements are rare in common law jurisdictions outside of the United States. Former Justice of the High Court of Australia William Gummow attributes the requirement for Restatements in the United States to the lack of a nationwide court of final common law adjudication.
The Restatement of the Law is one of the most respected and well-used sources of secondary authority, covering nearly every area of common law. While considered secondary authority (compare to primary authority), the authoritativeness of the Restatements of the Law is evidenced by their acceptance by courts throughout the United States. The Restatements have been cited in over 150,000 reported court decisions.