The group has asked the the US Federal Trade Commission (FTC) to place an injunction and temporary restraining order ahead of the 1 March transition, after which Google will consolidate the privacy policies for all of its web applications and services into a single document.
EPIC said in its complaint that Google's policy changes are in violation to a 2010 agreement the company entered into following the disastrous rollout of its Buzz service.
According to EPIC, part of that agreement required the company to notify users before sharing data and obtain consent.
EPIC said that Google's recent actions sit in direct violation of the agreement.
"Users will no longer be able to keep the personal information they provided to use the Google email service for simply that service," EPIC said in its filing.
"Google will be able to combine the user information provided for email with other Google services, including the Google social network service."
In addition to the complaint, EPIC has asked the FTC to file an injunction preventing the company from proceeding with its the policy changes.
Google, meanwhile, has hit back at the claims.
A company spokesperson told V3 that EPIC was mistaken in its claims and that no changes will be made to the company's policies on the sharing of user data.
He said Google is confident that the policy will pass third-party inspection.
"We take privacy very seriously," the spokespperson said.