The American Library Association says that filters are ineffective. The American Library Association, in arguing against the Communications Decency Act, argued that the CDA was unnecessary because filters were effective. Now that the CDA has been ruled unconstitutional, ALA has done a complete reversal and claims that filters are not effective.
Most filters rely on site selected blocking.
Better filters, such as Cyber Patrol, BESS, and Surf Watch, allow the user to turn the keyword blocking off. ALA is aware of this, yet ALA spokespeople continue to imply that all filtering is done with keyword blocking. Some filters do in fact do this, but the better filters usually break these things down by subject, allowing the user to choose which categories to block. The better filters, when set to block only pornography, do a good, though not perfect job of blocking only pornography. Inevitably, a small amount of innocent, useful information will blocked through human error.