their child patrons to use filtering software, but not their adult patrons.  

Filtering software vendors sell their products on a subscription basis.  The cost of

a subscription varies with the number of computers on which the filtering software will

be used.  In 2001, the cost of the Cyber Patrol filtering software was $1,950 for 100

terminal licenses.  The Greenville County Library System pays $2,500 per year for the

N2H2 filtering software, and a subscription to the Websense filter costs Westerville

Public Library approximately $1,200 per year. 

No evidence was presented on the cost of privacy screens, recessed monitors, and

the tap on the shoulder policy, relative to the costs of filtering software.  Nor did any of

the libraries proffered by the government present any quantitative evidence on the relative

effectiveness of use of privacy screens to prevent patrons from being unwillingly exposed

to sexually explicit material, and the use of filters, discussed below.  No evidence was

presented, for example, comparing the number of patron complaints in those libraries that

have tried both methods.

The librarians who testified at trial whose libraries use Internet filtering software

all provide methods by which their patrons may ask the library to unblock specific Web

sites or pages.  Of these, only the Tacoma Public Library allows patrons to request that a

URL be unblocked without providing any identifying information; Tacoma allows

patrons to request a URL by sending an email from the Internet terminal that the patron is

using that does not contain a return email address for the user.  David Biek, the head

librarian at the Tacoma Library's main branch, testified at trial that the library keeps

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