The practical effect of SOPA will be to create an architecture for censorship—both legal and technological—that will radically alter the costs of engaging in future censorship unrelated to piracy or counterfeiting … . [T]he portion of the bill laying out the specific types of criminal conduct that trigger this Rube Goldberg censorship machine occupy just a couple of paragraphs. With the legal framework in place, expanding it to cover other conduct—obscenity, defamation, “unfair competition,” patent infringement, publication of classified information, advocacy in support of terror groups —would be a matter of adding a few words to those paragraphs … . Any sane network operator is just going to build a filter that reads off the current list of banned domains from a government feed and automatically stops resolving them … . Once the up-front costs of implementing that filter mechanism are paid, the marginal cost of additional censorship is effectively zero for the providers.

Julian Sanchez: “SOPA: An Architecture for Censorship” writing at Cato@Liberty.