All day yesterday and today, the House Judiciary Committee has been debating its controversial Stop Online Piracy Act (SOPA). The Senate Judiciary Committee has already passed a similar bill. Copyright holders, including the music and film industries, say the new legislation is utterly essential for battling rampant Internet piracy. Opponents of the bills, including a diverse array of law professors and tech companies, have been shouting themselves hoarse arguing that the new bills will trample online speech and potentially “break” the Internet. So how problematic are these new piracy bills? Here’s a brief rundown.

(David Paul Morris/Bloomberg)

Wait, aren’t there already laws against online piracy? Yes. In 1998, Congress passed the Digital Millennium Copyright Act (DMCA), under which any site that’s hosting or linking to pirated material must promptly take down the offending material once notified. Google, for instance, says it has complied with more than 5 million takedown requests. Yet companies like Google or Facebook aren’t currently obliged to actively police their sites for illegal content, and, under the DMCA’s “safe harbor” provisions, service providers aren’t held liable for the content on their sites — so long as they make good-faith efforts to remove offending material when asked. Yet copyright holders say the current regime doesn’t go far enough.

Why do copyright holders need more drastic tools? As Tim Lee explains here, file-sharing has become increasingly decentralized as the record and movie industries have cracked down on infringers in the past decade. First they killed Napster, then went after more dispersed sites like Grokster, and now record labels are suing file-sharing individuals. But various hosting and link sites for pirated goods have been moving outside the United States, making it harder for the federal government to take them down. Essentially, copyright holders are asking for a really enormous sledgehammer to play this game of whack-a-mole.

Who’s for and against these piracy bills? The bills garner staunch support from groups that rely on copyright, such as the Motion Picture Association of America and the Recording Industry Association of America, as well as the Chamber of Commerce and the AFL-CIO, which has been convinced that online piracy cost jobs. The opposition forces include tech groups such as Google, Yahoo!, Twitter, eBay, and Wikimedia, as well as civil liberties groups such as the ACLU.

Why are tech start-ups so vehemently opposed? These companies have argued that the bills are tantamount to Internet censorship. Rather than receiving a notification for copyright violations, sites now face immediate action — up to and including being taken down before they have a chance to respond. Intermediary sites like YouTube and Flickr could lose their “safe harbor” protections. Nonprofit or low-budget sites might not have the resources to defend themselves against costly lawsuits. And, meanwhile, larger companies like Google and Facebook could be forced to spend considerable time and money policing their millions of offerings each day for offending material.

Do these online piracy bills threaten free speech? Plenty of law professors, including Harvard’s Laurence Tribe, think so. The original version of the bill would have allowed copyright holders to block advertising and payment services for an accused Web site before a judicial hearing even took place. The new version of the House bill would require a hearing first, but, as Julian Sanchez notes, the bill “still makes it far too easy for U.S. corporations to effectively destroy foreign Internet sites based on a one-sided proceeding in U.S. courts.” Other critics have worried that the bill’s language is far too broad, threatening all sorts of potentially benign Internet uses. What’s more, the Electronic Frontier Foundation worries that the bill cracks down on electronic tools to circumvent government blacklists that are essential to human rights activists and political dissidents around the world.

Could the bills actually “break” the Internet? Many tech experts think so. The bills would give courts the power to order rogue sites to be de-listed from the Domain Name System — basically, the Internet’s phone directory. U.S. service providers would be tasked with acting as if the site didn’t exist at all (although the newly revised House bill gives a little bit of flexibility here). A big potential pitfall here is that the Internet is global, and it’s possible that users could seek out foreign DNS servers to access blacklisted sites. Some experts have raised security concerns about this splintering of the Internet’s architecture.

Is all this even necessary? How big a problem is online piracy anyway? That’s unclear. Copyright providers often claim they’re losing huge fistfuls of money due to online piracy. $58 billion per year. $100 billion per year. Etc. Those numbers, however, are suspiciously hard to verify. And, at the moment, the content industry is doing better than the economy as a whole. What’s more, the whole point of copyright is, as the Constitution puts it, to “promote the progress of science and useful arts.” As James Fallows argues, overly aggressive enforcement of those rules can do just as much to stifle innovation as an overly lax approach can. The question is where the proper balance lies.

So how is this fight likely to play out? That’s unclear. If the House bill makes it out of committee, it could have a decent shot of passage. The Senate counterpart, already passed through committee, has been held up by Sen. Ron Wyden (D-Ore.). Out in the larger world, companies like Tumblr and Reddit have used their reach to whip up a large and vocal opposition among Internet users, though it’s far from certain that angry public opinion can sway Congress.

Perhaps the best shot at derailing the bills’ momentum comes from an alternative bill drawn up by Wyden and Rep. Darrell Issa (R-Calif.) that would provide more protections to Web sites accused of enabling infringement — they wouldn’t be cut off from ads and payment networks, for instance, until there was a full hearing by the International Trade Commission. Eric Goldman has a more detailed look at that alternative bill here.

Update: The House Judiciary Committee adjourned its hearings this afternoon without the expected vote on the bill. As David Kravets reports, no vote date has been set, which means the bill might not come up again until January at the earliest. Rep. Jason Chaffetz (R-Utah) motioned for the hearing to adjourn until technical experts could be brought in to testify on whether fiddling with the Domain Name System could pose security risks.