It goes far beyond trying to protect copyrighted material, and descends into "let's kill websites that are competitors." Youtube.com could be shut down if Google were to not take down a single, solitary video that was flagged by the industry within 5 days. A blog could be taken down is a single, solitary commenters quoted too extensively in a single comment. In effect, the internet would become like Cable TV, with megacorporations back to controlling almost all content, from the media, to books, music and film.
Here's a great explanation of how vast this bill goes, not only allowing sites to be targeted, but advertisers, and allowing content owners to seize sites without going through normal court channels, essentially throwing due process out the window.
Here's the comment, plucked from a Techcrunch blog. It should appear as the first comment below the article.
Certainly, the implications could be seen as a turning off of just about any avenue of the internet. The real problem here (addressing questions above) is that DOJ won't be doing the primary enforcement. SOPA grants jurisdiction for aggrieved holders of protected content to bring suit in addition to the DOJ. That means the "creator of the content" -- Metallica, let's just say -- or an agent of the aggrieved -- Metallica's record company -- will have jurisdiction in federal courts in the U.S. to bring suit against those websites that either a) control the location upon which the actual infringer posts the protected content, or b) against advertisers who help those websites continue to operate.
The requirements are that both the website and the advertiser be provided adequate notice of the infringement before suit can commence. That means enough time for the website to take appropriate action (removing the content and blocking the user, most likely), and any advertisers or "enablers" as I like to call them to discontinue business with those offending websites.
The problem is bigger than just the ability to regulate granted to the DoJ. The true problem is that it is giving the media outlets direct means of redress to bring suit not only against websites, many of which are unaware anything wrong is going on, and seek either or both monetary and injunctive relief, but also those advertisers (see facebook, google, etc.) who won't discontinue business with websites which host the offending content. In this light, it is clear that the media companies will now have the ability to sanction any web outlet, or web outlet that serves advertising, without addressing the underlying problem of the user who is doing the "offending" if we can call it that. Huge monetary sanctions against Google for advertising -- the stretches of this power could kill google as we know it (which may have been the underlying intent all along, as fond as they are of Google).
Let's say a commenter posts a link on small blog A to content that infringes on X's copyright. X might not care or know about it. But X's agent, RIAA, does. Someone likes the comment on blog A, and links on Facebook. On an aside, blog A uses Google advertising. The link on Facebook makes it into the internet's mainstream, in whatever way it will. It catches the attention of X's agent RIAA.
At this point, SOPA gives DOJ or the offended party (or her agent) a right to judicial redress by imposing monetary sanctions or achieving injunctive relief (shutting down the page, site, domain). At this point, Blog A, Google, Facebook, and every other site that served as host to the offending content are potentially liable. RIAA can pursue the action by notifying DOJ or by pursuing it individually after notice. In fact, RIAA could, under some circumstances, even TAKE THE DOMAINS of the offending website (under in rem property provisions in the H.R.).
Extrapolate the single instance to what stretches the entire internet, and well...the problem truly is vastly larger than what the DoJ could manage to enforce. That was never the true purpose though, was it?