From Wikipedia:
The Stop Online Piracy Act (SOPA), is a proposed law (bill) of the United States of America, to fight online trafficking in copyrighted intellectual property and counterfeit goods. Proposals include barring advertising networks and payment facilities from conducting business with allegedly infringing websites, barring search engines from linking to the sites, and requiring Internet service providers (ISP) to block access. The bill would criminalize streaming of content, with a maximum penalty of five years in prison.
In practice user-content websites such as Youtube would be greatly effected and websites like Etsy, Flickr and Vimeo all seemed likely to shut down if the bill becomes law. Opponents say the legislation would enable law enforcement to take down an entire domain due to something posted on a single blog, arguing, an entire online community could be punished for the actions of a tiny minority. In a 1998 law, copyright owners are required to request the site to remove the infringing material within a certain amount of time. SOPA would bypass this "safe harbor" provision by placing the responsibility for detecting and policing infringement onto the site itself.
Lobbyists claim it protects the intellectual property market and corresponding industry, jobs and revenue. The US president, and legislators suggest it may kill innovation. Representatives of the American Library Association state the changes could encourage criminal prosecution of libraries. Other opponents say that requiring search engines to delete a domain name begins a worldwide arms race of unprecedented censorship of the Web and violates the First Amendment
A number of protest actions were organized, including petition drives and boycotts of companies that support the legislation. On January 18 English Wikipedia and several other internet companies coordinated a service blackout to protest SOPA and PIPA.
The House Judiciary Committee held hearings on November 16 and December 15, 2011. The Committee was scheduled to continue debate in January 2012, but on January 17 Chairman Smith said that "Due to the Republican and Democratic retreats taking place over the next two weeks, markup of the Stop Online Piracy Act is expected to resume in February."