accompanied by a parent, or upon parental consent, or could
require minors to use unfiltered terminals in view of library
staff. To prevent patrons from being unwillingly exposed to
offensive, sexually explicit content, libraries can offer patrons
the option of using blocking software, can place unfiltered
terminals outside of patrons' sight lines, and can use privacy
screens and recessed monitors. While none of these less
restrictive alternatives are perfect, the government has failed
to show that they are significantly less effective than filtering
software, which itself fails to block access to large amounts of
speech that fall within the categories sought to be blocked.


In view of the severe limitations of filtering technology
and the existence of these less restrictive alternatives, we
conclude that it is not possible for a public library to comply
with CIPA without blocking a very substantial amount of
constitutionally protected speech, in violation of the First
Amendment. Because this conclusion derives from the inherent
limits of the filtering technology mandated by CIPA, it holds for
any library that complies with CIPA's conditions. Hence, even
under the stricter standard of facial invalidity proposed by the
government, which would require us to uphold CIPA if only a
single library can comply with CIPA's conditions without
violating the First Amendment, we conclude that CIPA is facially
invalid, since it will induce public libraries, as state actors,
to violate the First Amendment. Because we hold that CIPA is
invalid on these grounds, we need not reach the plaintiffs'
alternative theories that CIPA is invalid as a prior restraint on
speech and is unconstitutionally vague. Nor need we decide