The number of overblocked sites is of course much higher with respect to the definitions of obscenity and child pornography that CIPA employs for adults, since the filtering products’ category definitions, such as “sex” and “nudity,” encompass vast amounts of Web pages that are neither child pornography nor obscene.  Thus, the number of pages of constitutionally protected speech blocked by filtering products far exceeds the many thousands of pages that are overblocked by reference to the filtering products’ category definitions.

No presently conceivable technology can make the judgments necessary to determine whether a visual depiction fits the legal definitions of obscenity, child pornography, or harmful to minors.  Given the state of the art in filtering and image recognition technology, and the rapidly changing and expanding nature of the Web, we find that filtering products’ shortcomings will not be solved through a technical solution in the foreseeable future.  In sum, filtering products are currently unable to block only visual depictions that are obscene, child pornography, or harmful to minors (or, only content matching a filtering product’s category definitions) while simultaneously allowing access to all protected speech (or, all content not matching the blocking product’s category definitions).  Any software filter that is reasonably effective in blocking access to Web pages that fall within its category definitions will necessarily erroneously block a substantial number of Web pages that do not fall within its category definitions. 2.  Analytic Framework for the Opinion:  The Centrality of Dole and the Role of the Facial Challenge

Both the plaintiffs and the government agree that, because this case involves a challenge to the constitutionality of the conditions that Congress has set on state actors’ receipt of federal funds, the Supreme Court’s decision in South Dakota v.  Dole, 483 U.S. 203 (1987), supplies the proper threshold analytic framework.  The constitutional source of Congress’s spending power is Article I, Sec. 8, cl. 1, which provides that “Congress shall have Power . . . to pay the Debts and provide for the common Defence and general Welfare of the United States.”  In Dole, the Court upheld the constitutionality of a federal statute requiring the withholding of federal highway funds from any state with a drinking age below 21.  Id. at 211-12.  In sustaining the provision’s constitutionality, Dole articulated four general constitutional limitations on Congress’s exercise of the spending power.

First, “the exercise of the spending power must be in pursuit of ‘the general welfare.’” Id. at 207.  Second, any conditions that Congress sets on states’ receipt of federal funds must be sufficiently clear to enable recipients “to exercise their choice knowingly, cognizant of the consequences of their participation.”  Id. (internal quotation marks and citation omitted).  Third, the conditions on the receipt of federal funds