"More than 100 million people in the United States subscribe to the Facebook service. The company should not be allowed to turn down the privacy dial on so many American consumers," said Marc Rotenberg, executive director of the Electronic Privacy Information Center, in a statement.
Rotenberg said the changes will make too much user information available to the public, and also to third-party application developers that create games, contests, and other programs for Facebook.
In filing the case, EPIC said it received support from the American Library Association, the Center for Digital Democracy, the Consumer Federation of America, Patient Privacy Rights, and other advocacy groups.
Users' biggest complaint about the changes is that the default privacy setting on Facebook now opens their status updates to the entire Web, unless they proactively takes steps to modify the settings.
Facebook claimed Wednesday that it's implementing the changes in an effort to make it easier for members to control who can see which pieces of information they post.
"Facebook is transforming the world's ability to control its information online by empowering more than 350 million people to personalize the audience for each piece of content they share," said Facebook communications VP Elliot Schrage, in a statement.
Facebook added a tool that lets users select privacy settings for literally each post they place on the social networking site. Via a new dropdown menu, users can specify whether the post should be made to the general public, all their Facebook friends, or a list of particular friends, family members, or work colleagues.
Facebook also launched a "transition tool" to guide members through the new settings.
Additionally, Facebook is eliminating regional networks—user groups that allow members within a given geographical region to automatically share content with other network members. Facebook operates such networks around the world, including far-flung areas like India and China.
Facebook founder Mark Zuckerberg has said the regional networks are becoming too large to ensure members' privacy.