SOPA targets any site that contributed to copyright infringement, even if it was simply facilitating the act by providing a tool that could be used for illegal purposes (regardless of intention). PIPA, on the other hand, requires the targeted site to have no significant use beyond copyright infringement. Basically, PIPA can only be used to censor a site if it's more likely to be a source of illegal content than not. This is still problematic because a tool designed to accept user-generated content is, to some extent, at the whims of its users. If infringing content is found, rights holders already have the Digital Millenium Copyright Act (DMCA) to help them request the legal removal of that content. They also have the ability to sue infringers for damages, as we've previously seen with the Recording Industry Association of America (RIAA) when they, for example, sued a 12-year-old for downloading music. SOPA and PIPA provide a means to censor the tool that provided a means for the infringing content to exist on the internet rather than the content itself. This puts a lot of power in the hands of rights holders and has significant potential for abuse. This is, of course, our interpretation of these bills. Because we love the internet and oppose censorship, we have an obvious bias. While we believe the right thing to do is to oppose these bills, you should make an informed decision on your own. For more information, please read the exact content of both the SOPA and PIPA bills.