A law library is a special library maintained and supported by a legal organization that contains a collection of books, databases and other materials related to the organization's areas of specialization. Law libraries often, though not always, are controlled access collections. Circulation and use may be restricted.
 Types of Law Library
Like many special libraries, law libraries are often found in places not traditionally thought of as housing libraries. Law libraries are found in law schools and law firms as well as courts and other government agencies.
For example, every law school accredited by the American Bar Association is required to have a law library meeting certain minimum specifications with respect to quantity and quality of materials available. The United States Federal Courts also have law libraries, as do many of the state courts in the United States. Law firms sometimes also maintain law libraries for the use of their staffs. In addition, in some U.S. states, such as California, all counties are required to maintain a public law library for the benefit of the general public. (e.g. California Business and Professions Code Section 6300 et seq.)
 Legal Collections
A typical law library will include in its collection a large number of works not generally seen in other libraries, including federal and state statutes; the Code of Federal Regulations; law reporters such as the United States Reports; the Federal Register; volumes of legal encyclopedias such as American Jurisprudence; and law reviews, as well as a variety of legal treatises and practice guides.
Law libraries may also contain additional materials covering topics like legal education, legal history, legal ethics the legislative history of important federal and state statutes and other legal topics. However a small law library may contain only one unofficial Supreme Court reporter, selected West national reporters and digests specific to the state in which the library is located, the States Code, a few state-specific reporters and statutory compilations (if they exist for a particular state), and selected state-specific treatises and practice guides.
In recent years, the advent of online legal research outlets such as Westlaw, Lexis Nexis and Hein Online has reduced the need to keep some types of printed volumes like reporters and statutory compilations. A number of law libraries have therefore reduced the availability of printed works that can easily be found via these databases. It is important to note, however, that only a small fraction of legal publications have been digitized. Because of this, some law libraries -- especially academic law libraries -- continue to retain extensive print collections.
 ABA requirements for law school law libraries in the US
As of 2010, the American Bar Association has propounded rules requiring each accredited law school in the United States to have a law library that includes among its holdings the following "core collection":
- all reported federal court decisions and reported decisions of the highest appellate court of each state;
- all federal codes and session laws, and at least one current annotated code for each state;
- all current published treaties and international agreements of the United States;
- all current published regulations (codified and uncodified) of the federal government and the codified regulations of the state in which the law school is located;
- those federal and state administrative decisions appropriate to the programs of the law school;
- U.S. Congressional materials appropriate to the programs of the law school;
- significant secondary works necessary to support the programs of the law school, and
- those tools, such as citators and periodical indexes, necessary to identify primary and secondary legal information and update primary legal information.
The ABA further sets forth additional requirements, including the requirement that the law library have a full-time director, and sufficient staff to attend to the needs of the institution.
 Professional Associations
Two professional associations, the American Association of Law Libraries (AALL) and the Special Libraries Association (SLA) represent the interests of law librarians in the United States and Canada. In addition, the International Association of Law Libraries (IALL) has members from over 50 countries and represents law libraries internationally. As of 2010, AALL has over 5,000 member libraries.