6. What if a library board is asked to use movie, video game, music, or other ratings to restrict access?

A variety of private organizations — including the Classification and Rating Administration (CARA) of the Motion Picture Association of America (MPAA), Canadian Motion Picture Distributors Association (MPA Canada), PSV ratings Standards Board (PSV), Parents Television Council (PTC), Entertainment Software Rating Board (ESRB), TV Parental Guidelines Monitoring Board, and the Recording Industry Association of America (RIAA) — have developed rating systems as a means of advising parents concerning their opinions of the contents and suitability or appropriate age for use of certain books, films, recordings, television programs, websites, or other materials.

None of these organizations are government agencies and as such their rating systems cannot be mandated or enforced by any government or agency, including a publicly funded library. This applies with equal force to library policies and procedures that effectively deny minors equal and equitable access to library resources and services available to other users. A library can, however, make information concerning these rating systems available to library patrons.

For more information on this topic, see Deborah Caldwell-Stone’s "Movie Ratings are Private, Not Public Policy" from the Illinois Library Association Reporter (2004).

Source:  http://www.ala.org/advocacy/intfreedom/labelingratingqa