A pocket part is an addendum sent out by a publisher of a legal text that updates the information contained within a particular book. The nature of law is that it is ever changing; the facts that are contained within a legal text may become outdated soon after publication. Rather than publish entire runs of new books with a few minor changes, publishers send out small packets to be attached to the back of the corresponding book so its reader can access the most current information. The pocket part is typically attached to the inside of the back cover of the book, which makes it easily apparent to any of the book’s readers. The emergence of computers and the Internet has made pocket parts obsolete for the most part as publishers may just keep an updated database online rather than continually sending out updates through the mail.
Coming in the form of a small pamphlet, a pocket part is attached to the back of a legal text. It is typically not very thick as it contains the small updates that have occurred since the original text's publication. The reader usually researches the law contained in the original published version of the book, and then consults the pocket part in order to see if there have been any updates since the book's original publication. This provides the most current information for the reader.
Pocket parts have been produced as long as there has been mass production of legal texts. Publishers first came up with the idea after seeing that new legislation can render the information contained within legal book obsolete. The reliability of the information published in these texts was incredibly important to the publishers, as their clientele was mostly made up of legal professionals who used them as the basis for their practice. Publishers realized they could either go through the impractical process of continually producing updated texts with minor changes or come up with another less expensive and more practical method of updating the information. For this reason, the pocket part was created.
Technological advances have made information infinitely more accessible than it was in the days that the idea for the pocket part was conceived. Contemporary producers of legal texts typically maintain all their information in various databases on the Internet. This has the dual effect of making information more accessible to legal professionals and easier for the publisher to update when lawmakers enact changes to the various laws.