Primary vs. Secondary, Overview
The sources of legal authority can be classified as primary or secondary.
Primary Sources
Primary sources are those that contain binding authority, such as statutes, regulations and controlling case law.
Primary law is controlling law. It is issued or enacted by a governmental body.
Examples are statutes passed by legislatures, rules enacted by an administrative agency, and court rulings handed down by courts where their decisions have binding force. Primary sources contain “the law.” The law generated by those three branches of government can be summarized as:
Legislative:
Statutes, laws and ordinances enacted at the federal, state, county and municipal levels.
Judicial:
Caselaw and the resulting precedent (doctrine of stare decisis).
Administrative:
Agency regulations and other administrative orders.
Secondary Sources
Secondary sources (or authority) consist of everything else.
Such authority does not have a controlling or mandatory effect, but is only persuasive. It is not the law; rather it seeks to explain, comment on, or propose changes to the law. Legal encyclopedias, treatises, law reports and law review articles are examples of secondary authority sources.
Pocket Parts
Fig. 1: Separate pocket part inside back-cover slot of a print volume
Even as more research gets done done online, this still bears repeating: whenever you are using a printed legal book, check for a pocket part to the main volume you are reading.
Online databases and sources are updated quickly. The online information is usually current and valid.
Printed hardbound books, however, may not be reprinted annually. In order to keep them current the books have a pocket inside the back cover. Stapled looseleaf updates are inserted in that pocket, hence the name 'pocket parts'.
Always look for the pocket part and refer to the section you were researching to find the latest information.