The American Library Association affirms that all libraries are forums for information and ideas, and that the following basic policies should guide their services.
1. Books and other library resources should be provided for the interest, information, and enlightenment of all people of the community the library serves. Materials should not be excluded because of the origin, background, or views of those contributing to their creation.
2. Libraries should provide materials and information presenting all points of view on current and historical issues. Materials should not be proscribed or removed because of partisan or doctrinal disapproval.
3. Libraries should challenge censorship in the fulfillment of their responsibility to provide Information and enlightenment.
http://www.ala.org/advocacy/intfreedom/librarybill