Writing on Slaw on The “Great Encyclopedias” of Legal Research, Gary P. Rodrigues describes the common law tradition of legal encyclopedia publishing.
The roots of such encyclopedias are in a systematic attempt to reduce to an authoritative format, the common law and statutory law of a given jurisdiction. They eschew “legal realism” and artfully weave a statement of the law as set forth by judges, statutes, and rules (even though these sources may not always provide a complete picture of reality on the ground) by way of analyzing and organizing those judicial decisions, statutes and other rules relevant to the topic or point of law.
West’s Corpus Juris Secundum has been a national (U.S.) legal encyclopedia for roughly a century. Forerunner Corpus Juris was introduced in 1914. (The Wikipedia entry has the year as 1911.)