Rare book dealers and collections often use their own system for organizing materials.
"American law libraries contain large, diffuse collections since, pursuant to the common law, much of our law is "found" or "made" by judicial decisions. Determining the decisions of present cases on the basis of precedents results in legal literature accumulating and assuming large proportions. Another factor resulting in the growth of American legal collections is the multiple system of state and federal laws which makes necessary the acquisition and maintenance of primary sources for fifty states as well as those of the federal government" (3). These huge collections are normally organized according to rules created more than a century ago. The only reasonable approach for the layman is to get the help of a law librarian.
Indeed, for any library using a nonstandard classification system, the best approach is to depend on the expertise of the local librarian.
Please send comments to: Colby Glass, MLIS