Critics, among them the founders of Google, Wikipedia, the Internet Archive, Tumblr and Twitter, counter that the laws will stifle innovation and investment, hallmarks of the free, open Internet. The Obama administration has offered muted criticism of the legislation, but, as many of his supporters have painfully learned, what President Barack Obama questions one day he signs into law the next.

First, the basics. SOPA stands for the Stop Online Piracy Act, while PIPA is the Protect IP Act. The two bills are very similar. SOPA would allow copyright holders to complain to the U.S. attorney general about a foreign website they allege is “committing or facilitating the commission of criminal violations” of copyright law. This relates mostly to pirated movies and music. SOPA would allow the movie industry, through the courts and the U.S. attorney general, to send a slew of demands that Internet service providers (ISPs) and search-engine companies shut down access to those alleged violators, and even to prevent linking to those sites, thus making them “unfindable.” It would also bar Internet advertising providers from making payments to websites accused of copyright violations.

SOPA could, then, shut down a community-based site like YouTube if just one of its millions of users was accused of violating one U.S. copyright. As David Drummond, Google’s chief legal officer and an opponent of the legislation, blogged, “Last year alone we acted on copyright takedown notices for more than 5 million webpages.” He wrote, “PIPA & SOPA will censor the web, will risk our industry’s track record of innovation and job creation, and will not stop piracy.”

Corynne McSherry, intellectual property director at the Electronic Frontier Foundation (EFF.org), told me: “These bills propose new powers for the government and for private actors to create, effectively, blacklists of sites … then force service providers to block access to those sites. That’s why we call these the censorship bills.”

The bills, she says, are the creation of the entertainment, or “content,” industries: “SOPA, in particular, was negotiated without any consultation with the technology sector. They were specifically excluded.” The exclusion of the tech sector has alarmed not only Silicon Valley executives, but also conservatives like Utah Republican Congressman Jason Chaffetz, a tea party favorite. He said in a December House Judiciary Committee hearing, “We’re basically going to reconfigure the Internet and how it’s going to work, without bringing in the nerds.”