Most of the libraries that use filtering software seek to block sexually explicit speech.  While most libraries include in their physical collection copies of volumes such as The Joy of Sex and The Joy of Gay Sex, which contain quite explicit photographs and descriptions, filtering software blocks large quantities of other, comparable information about health and sexuality that adults and teenagers seek on the Web.  One teenager testified that the Internet access in a public library was the only venue in which she could obtain information important to her about her own sexuality.  Another library patron witness described using the Internet to research breast cancer and reconstructive surgery for his mother who had breast surgery. 
 Even though some filtering programs contain exceptions for
health and education, the exceptions do not solve the problem of
 overblocking constitutionally protected material.  Moreover, as
we explain below, the filtering software on which the parties presented evidence in this case overblocks not only information relating to health and sexuality that might be mistaken for pornography or erotica, but also vast numbers of Web pages and sites that could not even arguably be construed as harmful or inappropriate for adults or minors.

The Congress, sharing the concerns of many library boards, enacted the Children’s Internet Protection Act ("CIPA"), Pub.  L. No. 106-554, which makes the use of filters by a public library a condition of its receipt of two kinds of subsidies that are important (or even critical) to the budgets of many public libraries – grants under the Library Services and Technology Act, 20 U.S.C.  Sec. 9101 et seq. ("LSTA"), and so-called “E-rate discounts” for Internet access and support under the Telecommunications Act, 47 U.S.C.  Sec. 254.  LSTA grant funds are awarded, inter alia, in order to:  (1) assist libraries in accessing information through electronic networks, and (2) provide targeted library and information services to persons having difficulty using a library and to underserved and rural communities, including children from families with incomes below the poverty line.  E-rate discounts serve the similar purpose of extending Internet access to schools and libraries in low-income communities.  CIPA requires that libraries, in order to receive LSTA funds or E-rate discounts, certify that they are using a “technology protection measure” that prevents patrons from accessing “visual depictions” that are “obscene,” “child pornography,” or in the case of minors, “harmful to minors.” 20 U.S.C.  Sec. 9134(f)(1)(A) (LSTA); 47 U.S.C.  Sec. 254(h)(6)(B) & (C) (E-rate).