Harvard Law School constitutional expert Laurence Tribe believes the Stop Online Piracy Act (SOPA) is unconstitutional.

The legal figure sent a letter to members of Congress this past week, saying that SOPA violates the First Amendment and leads to illegal "prior restraint."

Tribe also criticized the new provisions in the bill targeting websites' finances.

"This provision of the bill would give complaining parties the power to stop online advertisers," he wrote in the letter. "And credit card processors from doing business with a website, merely by filing a unilateral notice accusing the site of being "dedicated to the theft of the U.S. property."

(Photo credit: Eric Brown)