it may be quite harmful. The volume of pornography on the
Internet is huge, and the record before us demonstrates that
public library patrons of all ages, many from ages 11 to 15, have
regularly sought to access it in public library settings. There
are more than 100,000 pornographic Web sites that can be accessed
for free and without providing any registration information, and
tens of thousands of Web sites contain child pornography.
Libraries have reacted to this situation by utilizing a
number of means designed to insure that patrons avoid illegal
(and unwanted) content while also enabling patrons to find the
content they desire. Some libraries have trained patrons in how
to use the Internet while avoiding illegal content, or have
directed their patrons to "preferred" Web sites that librarians
have reviewed. Other libraries have utilized such devices as
recessing the computer monitors, installing privacy screens, and
monitoring implemented by a "tap on the shoulder" of patrons
perceived to be offending library policy. Still others, viewing
the foregoing approaches as inadequate or uncomfortable (some
librarians do not wish to confront patrons), have purchased
commercially available software that blocks certain categories of
material deemed by the library board as unsuitable for use in
their facilities. Indeed, 7% of American public libraries use
blocking software for adults. Although such programs are
somewhat effective in blocking large quantities of pornography,
they are blunt instruments that not only "underblock," i.e., fail
to block access to substantial amounts of content that the
library boards wish to exclude, but also, central to this
litigation, "overblock," i.e., block access to large quantities
of material that library boards do not wish to exclude and that
is constitutionally protected.