Today is American Censorship Day. A coalition of Internet activists, joined by some of the largest sites on the Web, invented this day to protest the Stop Online Piracy Act, legislation which had its first hearing in the House Judiciary Committee today. Predictably, the Judiciary Committee only featured panelists who supported the legislation. So to find a critique of the bill (or its companion, the Protect IP Act), you had to go to the Web. Alternatively, you could have opened your New York Times this morning to find a full-page ad:

We support the bill’s stated goals – providing additional enforcement tools to combat foreign “rogue” websites that are dedicated to copyright infringement or counterfeiting. Unfortunately, the bills as drafted would expose law-abiding US Internet or technology companies to new and uncertain liabilities, private rights of action, and technology mandates that would require monitoring of websites.

There’s a lot more in the ad. It was signed by companies like eBay, Facebook, AOL, Google, Twitter, Yahoo, Zynga, LinkedIn and Mozilla. Potentially all of those sites or offshoots of them could be shut down merely if a user posts copyrighted material to their site. This sets up an impossible standard, and is a precursor to shutting down a giant chunk of the Internet, creating a vacuum into which content producers and gatekeepers would flow.

In short, the bill creates an Internet blacklist. And with most of Congress, at least those paying attention to the issue (in no small part because of payoffs from major content producers like the movie and music industry), supporting the bill, it will take the power of these Internet companies to stop it.

Mel Watt, a North Carolina Democrat and one of the bill’s sponsors, dismissed as “hyperbolic” charges the bill “will open the floodgates to government censorship.” He said the comments belittled “the circumstances under which true victims of tyrannical governments actually live.”

The act has powerful support from the United States Chamber of Commerce, the Motion Picture Association of America, the American Federation of Musicians, the Directors Guild of America, the Screen Actors Guild and drug companies keen for a crack down on online pharmacies undercutting US sales.

But it has met with almost universal criticism from the tech community. Mozilla, maker of the Firefox web browser, blacked out its name on its home page in an anti-Sopa protest, as did Reddit, the social news site. Tumblr launched a page attacking the act, and firms including AOL, eBay, Facebook, Google, Twitter and Zynga criticised Sopa in a full-page advertisement in The New York Times.

Fight for the Future is the main coalition lobbying against the bill, but it has the support of a broad community, including RedState. The main champion on Capitol Hill is Sen. Ron Wyden, who has vowed to place a hold on the bill. Without public attention, however, that probably won’t be enough.

UPDATE: Organizers announce that over 23,000 emails per hour are being sent to Congress as a result of their action, and 3.6 calls per second are being generated through Tumblr.