Legislation aimed at combating online piracy has been attacked by internet giants, including Facebook and Google. They say the proposed act is too strict and would encourage censorship – essentially creating an "internet blacklist bill", according to the Guardian.
The Stop Piracy Online Act (SOPA) aims to crack down on copyright and trademark issues in the US.
"As we all know, the internet harbours a category of bad faith actors whose very business models consist of infringing copyright in American books, software, movies, and music with impunity," said Maria Pallante, register of copyrights.
She said these "rogue" sites were the "dark side of the internet".
The act will require "all key members of the online ecosystem, including service providers, search engines, payment processors, and advertising networks, to play a role in protecting copyright interests".
However, hundreds of sites have begun using "STOP CENSORSHIP" logos. Google, AOL, eBay, Facebook, LinkedIn, Mozilla, Twitter, Yahoo and Zynga have all lodged a formal letter of complaint.
"We support the bills' stated goals," the letter reads. "Unfortunately, the bills as drafted would expose law-abiding US internet and technology companies to new uncertain liabilities [and] mandates that would require monitoring of websites."
Blogging site Tumblr blacked out words in its content feeds and activated a banner at the top of dashboards reading: "Stop The Law That Will Censor The Internet".
Google's executive chairman Eric Schmidt has called the bill "draconian" this week.
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