Internet Filter Effectiveness: Testing Over and Underinclusive Blocking Decisions of Four Popular Filters

In the wake of the Littleton, Colorado shooting tragedy, public attention has again been focused on the problem of potentially harmful Internet content. Many parents and legislators have proposed that commercially available filtering software is the best way to keep children away from the "red light districts of cyberspace," while also protecting the First Amendment. Civil libertarians and others however, have noted that Internet content filters do not work as advertised, failing to block much dangerous material, while also unjustly blocking benign content. The aim of this paper is to asses these competing claims by rigorously testing the effectiveness of four popular filtering programs: CYBERsitter, Cyber Patrol, Net Nanny, and SurfWatch. The findings of this study suggest that current support for filtering software should be reconsidered.