Editor’s note: Laurence Tribe teaches Constitutional Law at Harvard Law School where he is the Carl M. Loeb University Professor, Harvard’s highest academic honor.

Last week, the House Judiciary Committee held a markup on H.R.3261, the Stop Online Piracy Act or “SOPA,” a bill to address the problems of online copyright and trademark infringement.  The controversial nature of the legislation is reflected by the fact that Members offered more than 55 amendments to the legislation, and the markup could not be completed as scheduled.  The Committee has announced that the markup will resume on December 21.

Stealing music, movies, and other forms of copyrighted materials is wrong, and the problem of online infringement is real.  But the bill is not an appropriate solution.  It’s a blunderbuss rather than a more narrowly tailored response, and its stiff penalties would pose a significant risk to legitimate websites and services.  It would undermine the openness and free exchange of information at the heart of the Internet.  And it would violate the First Amendment.

A key provision of the bill would give copyright owners the power to stop online advertisers and credit card processors from doing business with a website, merely by filing a unilateral notice that the site is “dedicated to the theft of U.S. property” – even if no court has actually found that infringement has occurred.  The immunity provisions in the bill create an overwhelming incentive for advertisers and payment processors to comply with such a request upon receipt.  Courts have always treated such cutoffs of revenue as a suppression of speech, and the silencing of expression in the absence of judicial review is a classic prior restraint forbidden by the First Amendment.

Moreover, the bill’s definition of a site “dedicated to” theft is vague and subjective, in violation of longstanding constitutional precedent that rules regulating speech must give clear notice of what they prohibit.  The ambiguous definition will impermissibly chill protected communication.

For example, the definition includes websites that take actions to “avoid confirming a high probability of … use” for infringement.  Absence of knowledge of specific infringing acts would not be a defense.  Thus, the definition would effectively require sites actively to police themselves to ensure that infringement does not occur.  For sites with substantial user-generated content, such as Facebook, Twitter, and YouTube, the burden would be considerable.  Blogs that allow users to post videos, photos, and other materials would also face penalties.

In effect, the bill would impose the very monitoring obligation that existing law (in the form of the 1998 Digital Millennium Copyright Act) expressly does not require.  Until now, Congress has promised online services a safe harbor against copyright liability so long as they take down allegedly infringing material when notified of the violation.  The bill would undo the very statutory framework that has created the foundation for many web-based businesses.

To compound the burden, the proposed bill does not proceed on a page-by-page or link-by-link basis, unlike current law.  Under the bill, if a single page on a 1,000-page website were deemed to infringe, the entire website could be deemed to be in violation.

Another section of the bill would allow the Attorney General to sue foreign websites that allegedly “facilitate” infringement and require blocking by U.S. service providers, search engines, and others.  In many cases, it seems unlikely that the government’s allegations would ever be tested, since foreign sites will often be unwilling to enter a U.S. court.  In the meantime, the blacklist would deny the right of U.S. audiences to receive the information – at the very time our government criticizes other countries for denying their citizens access to websites that lack official approval.

The danger to constitutionally protected communication has not gone unnoticed.  Representatives Zoe Lofgren (D-CA) and Darrell Issa (R-CA) have circulated a letter opposing SOPA to their colleagues in the House.  The two explained that they would instead support “narrowly targeted legislation that does not ensnare legitimate websites.”  In fact, Rep. Lofgren warned that SOPA “would mean the end of the Internet as we know it.”  Earlier this year, some 108 law professors sent a letter to Congress arguing that the Senate version of the bill, which contains the same harmful provisions, raises serious constitutional questions under the First Amendment.

The House bill’s sponsors recognize the importance of the issues.  They’ve included language stating “[n]othing in this Act shall be construed to impose a prior restraint on free speech or the press protected under the 1st Amendment to the Constitution.”  But saying the bill is constitutional does not make it so.  In fact, the proviso may have the unintended effect of rendering inoperative large swaths of the bill.  If that’s the case, wouldn’t it make sense for all involved to go back to the drawing board and craft a new measure that works as a scalpel rather than a sledgehammer?

Professor Tribe has been retained by the Consumer Electronics Association even though the views expressed are his own.