companies is identical to CIPA’s definitions of visual depictions that are obscene, child pornography, or harmful to minors.  And category definitions and categorization decisions are made without reference to local community standards.  Moreover, there is no judicial involvement in the creation of filtering software companies’ category definitions and no judicial determination is made before these companies categorize a Web page or site.

Each filtering software company associates each URL in its control list with a “tag” or other identifier that indicates the company’s evaluation of whether the content or features of the Web site or page accessed via that URL meets one or more of its category definitions.  If a user attempts to access a Web site or page that is blocked by the filter, the user is immediately presented with a screen that indicates that a block has occurred as a result of the operation of the filtering software.  These “denial screens” appear only at the point that a user attempts to access a site or page in an enabled category.  All four of the filtering programs on which evidence was presented allow users to customize the category lists that exist on their own PCs or servers by adding or removing specific URLs.  For example, if a public librarian charged with administering a library’s Internet terminals comes across a Web site that he or she finds objectionable that is not blocked by the filtering program that his or her library is using, then the librarian may add that URL to a category list that exists only on the library’s network, and it would thereafter be blocked under that category.  Similarly, a customer may remove individual URLs from category lists.  Importantly, however, no one but the filtering companies has access to the complete list of URLs in any category.  The actual URLs or Ip addresses of the Web sites or pages contained in filtering software vendors’ category lists are considered to be proprietary information, and are unavailable for review by customers or the general public, including the proprietors of Web sites that are blocked by filtering software.

Filtering software companies do not generally notify the proprietors of Web sites when they block their sites.  The only way to discover which URLs are blocked and which are not blocked by any particular filtering company is by testing individual URLs with filtering software, or by entering URLs one by one into the “URL checker” that most filtering software companies provide on their Web sites.  Filtering software companies will entertain requests for recategorization from proprietors of Web sites that discover their sites are blocked.  Because new pages are constantly being added to the Web, filtering companies provide their customers with periodic updates of category lists.  Once a particular Web page or site is categorized, however, filtering companies generally do not re-review the contents of that page or site unless they receive a request to do so, even though the content on individual Web pages and sites changes frequently. 2.  The Methods that Filtering Companies Use to Compile Category Lists