For more of the reasons why opponents of the bill have declared today "American Censorship Day," go to the ACD site, or Fight for the Future, or Mozilla's site. And for a how-to of Internet censorship a la Chinoise, there is this Atlantic piece from three years ago, still basically true to the operations of the Great Firewall. In the NYT Rebecca MacKinnon makes the Great Firewall-SOPA connection.
The Vimeo clip below does a very clear and concise job of explaining the commercial, technical, and political issues at stake. Short description of the problem: in the name of blocking copyright-infringing piracy sites mainly outside the United States, the bill would make U.S.-based Internet companies legally liable for links to or publication of any pirated material. This would be technically cumbersome, economically and commercially dampening, and potentially politically repressive. The video tells you more.
PROTECT IP Act Breaks The Internet from Fight for the Future on Vimeo.
Every developed society has had to work out the right balance of how
far it will go to ensure that inventors and creators will get a
reasonable return for their discoveries. If it does too little -- as in
modern China, where you can buy a DVD of any movie for $1.50 from a
street vendor -- it throttles the growth of creative industries. (China
both over-controls political expression and under-controls commercial
copying.) If it does too much -- encouraging "patent troll" lawsuits,
arresting people for file-sharing music or video streams -- it can
throttle growth and creativity in other ways. There is no perfect
answer, but this bill would tip the balance way too far in one
direction, to defend incumbents in the entertainment industry.
And for a wonderful illustration of the completely unexpected ways in which technological, political, commercial, and social creativity can interact, by all means read Alexis Madrigal's item on "OWS as API."