There's a lot of problems with SOPA and PIPA. But the big ones as far as fanworks seem to be that 1) sites must be shut down or blocked based on accusation alone; and 2) the shut down or blocking of entire sites based on one act of alleged infringement. Nearly all fanworks can be construed to be an infringement of intellectual property. I'm not saying it is or isn't - I'm just saying that as long as you aren't the copyright holder and your fanwork clearly references material owned by the accuser (like mentioning Sam and Dean Winchester, or using a picture of them), then a valid, preliminary legal argument can be made that you might be infringing. Based on that alone, in the earlier version of the bill I read in December, they could require the architects of the internet to block every part of your website. It operates like a cease-and-desist order, where your accuser says you're doing something annoying and you are legally required to stop that action, based on the mere receipt of a letter telling you to. You don't get to defend yourself before stopping and they don't have to prove anything. The only choices the accused have is to give up on ever doing the accused activity again, or take the accuser to court so you can prove your innocence.
If that sounds a bit ass-backwards, given that this is the US, that's only because this is the less-well-publicized, less-racy civil law we're talking about now and not the higher profile, innocent-until-proven-guilty criminal law. Civil law has some provisions in there that allow the legal system to interfere with someone without any proof whatsoever. Sort of like how my ex can assert in the course of our divorce that I must produce copies of all our financial documents (fair enough), including ones I don't have (wtf?), require me to contact everyone we've ever done business with and get their records of us (OMG, what a pain in the ass! don't you know I have a job?!?), copy every calendar we ever had in the course of the marriage (whoa ... no way?), every note that I ever took (now that's just stupid), every email I sent to anyone that mentioned the divorce or him (thank god he didn't ask for this, but he could have), screen caps of any posts I made on social media sites referencing the divorce or him (again, thank god his attorney is an old fart and didn't include this), my diary (I don't have one, thank goodness), personal journals (again, don't have, if you don't count LJ), etc. He can ask me for all this stuff and put an enormous burden of effort on me, and if I don't provide it, I can be fined or jailed (should he be able to prove that I failed).
Civil law provides many ways to harass people that criminal law does not. The claws of SOPA and PIPA in the December version was that it allowed all that web blocking without them having to prove anything more than that your site contained their copyrighted material. Then they essentially told the internet gods to cease and desist on allowing your site to exist. You could challenge it, sure, but how many of you want to dish out thousands of dollars, or more, to have the right to put up a website of your fanwork? Even if you did, even if you won, if you posted a new fanwork, they could start the process all over again.
Anyway, here's a round-up of some media statements on the result of the black-out (reposted from nrrrdy_grrrl):
"The SOPA and PIPA bills appear to have lost critical political support after yesterday's blackout protests by Wikipedia, Google, et al. However, there's now a new bill, known as Online Protection and Enforcement of Digital Trade (OPEN). In IT Blogwatch, bloggers wonder if this one is just as one-sided, unconstitutional, and unworkable as the previous efforts."
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Computer World "This isn't the end. The SOPA/PIPA bills have not yet been decided (that happens next week), so we need to keep telling American congresscritters that this legislation will damage the public's online freedoms -- and how."
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The Guardian "SOPA protest works: key supporters of bills back off. The Internet community’s rally cry against anti-piracy legislation is triggering its intended effect, though the final outcome remains far from settled."
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Toronto Star "Six U.S. lawmakers dropped their support for Hollywood-backed anti-piracy legislation as Google Inc., Wikipedia and other websites protest the measures."
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Business Week "SOPA, PIPA lose support from lawmakers on Capitol Hill amid blackout."
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The Washington Post "SOPA Author Lamar Smith (R-TX) Breaks Copyright Law on His Own Website"
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Burnt Orange Report