Craigslist and Reddit are among tens of thousands of websites that are protesting the proposed Cyber Intelligence Sharing and Protection Act, which they say is a threat to Internet users' privacy under the guise of a security measure.

Better known as CISPA, the bill has also been questioned by US politicians – but for different reasons to the web-protesters. The opposed legislators claim CISPA doesn’t go far enough to protect Americans online.

Spearheading the effort, along with Craigslist and Reddit, are the Internet Defense League and the Electronic Frontier Foundation, two digital rights organizations who were outspoken against the proposed SOPA/PIPA legislation in early 2012. The Internet Defense League includes Mozilla, WordPress, Fark.com, Imgur and Tech Dirt among its members. The Electronic Frontier Foundation describes itself as an advocate that began “well before the Internet was on most people’s radar and continues to confront cutting-edge issues defending free speech, privacy, innovation, and consumer rights today.”

Social discussion site Reddit posted an “action tool” on its front page allowing users to directly contact their Congressional representatives with an automated message. “CISPA is Back. This bill sacrifices privacy without improving security. We deserve both,” the message reads, while a link on classifieds website Craigslist reads: “Pro Privacy? Oppose CISPA.”

The bill failed to pass through Congress last year but was reintroduced in February by Reps. Mike Rogers (R-Mich.) and Dutch Ruppersberger (D-Md.). That news prompted more than 300,000 Internet activists to sign a petition against the bill, a plea that was then emailed to the House Intelligence Committee.

If a version of CISPA is passed in its current form, businesses and government agencies would have the legal power to share cyber information they collect about users. The bill's proponents say it’s necessary in order to keep up with hackers - who often leave identifiable 'signatures' after infiltrating a site - while privacy advocates have said the bill’s current definition of data is far too broad, risking infringement on civil liberties.

Major tech companies including Google and Microsoft, as well as telecommunication giants like Verizon and AT&T, have come out in support of CISPA.

In early March a separate petition against CISPA surpassed 100,000 signatures, the number required by the Obama administration to warrant an official response from the White House. That statement is still forthcoming, but last year President Obama threatened to veto the bill, saying, “Cybersecurity and privacy are not mutually exclusive.”

The US House of representatives is expected to vote on CISPA in April. Obama has not reiterated his threat to veto the bill, but his aides did say earlier this year that he hoped Congress would start a productive conversation regarding cyber threats.

