Wikipedia's pledged to shutter its website tomorrow in protest at the proposed Stop Online Piracy Act (SOPA) and Protect IP (PIPA) bills.
Starting at 05:00 UTC, the English language site will go dark fir 24 hours - apart from articles about SOPA and PIPA themselves, and a message urging readers to take their concerns to Congress.
The German and Italian versions, along with Wikimedia Commons, will display banner notices protesting about the bills.
Like many other organizations, Wikipedia believes that the bills are a serious threat to the freedom of the internet. They could force website owners to continually monitor whether they're hosting copyright-infringing material, and would give the US the 'right' to cut off access to foreign websites.
"Today, Wikipedians from around the world have spoken about their opposition to this destructive legislation," says Wikipedia founder Jimmy Wales.
"This is an extraordinary action for our community to take - and while we regret having to prevent the world from having access to Wikipedia for even a second, we simply cannot ignore the fact that SOPA and PIPA endanger free speech both in the United States and abroad, and set a frightening precedent of internet censorship for the world."
The move follows similar announcements from other websites including Reddit, and forceful opposition from the likes of Google, Facebook and Sony.
However, other key internet players will remain open for business, with Twitter CEO Dick Costolo calling the closures 'foolish'.
Moves to defeat the legislation gained a significant boost late last week, when the White House said it wouldn't back certain key parts of the bills.
"While we believe that online piracy by foreign websites is a serious problem that requires a serious legislative response, we will not support legislation that reduces freedom of expression, increases cybersecurity risk, or undermines the dynamic, innovative global internet," officials said in a statement.
However, opponents warn that the bills could easily be revived, and that the fight must continue.
"The concerns that have been expressed are too serious to try to address on the fly in a hurried manager’s amendment, without the benefit of any further hearings or the kind of input the White House statement suggests," says pressure group The Center for Democracy and Technology.