Yesterday, the Supreme Court again blocked enforcement of the Child Online Protection Act (COPA), citing that it has not yet been proved that voluntary use of Internet filters would not work as well as legally enforced use. COPA penalizes entities for material that is "harmful to minors", therefore restricting speech and arguably violating the First Amendment. In today's New York Times, Professor Jonathan Zittrain comments on this, explaining that filters may easily be turned into censors if required by law.