A formal complaint was recently filed with the FCC by the Electronic Privacy Information Center against Facebook, claiming that when the social media giant conducted a psychological research study back in 2012, they did it without the consent of their users.

The complaint states that “The company purposefully messed with people’s minds,” and went on to say that “At the time of the experiment, Facebook did not state in the Data Use Policy that user data will be used for research purposes.”

The complaint also said that users were not informed by Facebook that researchers would have access to their personal information (The original story, and more information, can be found here).

Facebook, not surprisingly, responded immediately to the complaint, saying that “When someone signs up for Facebook, we’ve always asked permission to use their information to provide and enhance the services we offer.”

Forbes magazine however pointed out that, while their policy might permit Facebook to do it now, back in 2012 when the study actually took place their Data Used Policy didn’t cover their study or its “emotion manipulation”.

Facebook believes that they were in the right, saying in effect that it’s normal for companies who want to improve their services to use any information that their customers might provide. In the UK however, the social media giant is already in hot water over the psychological experiment.

In fact, Facebook seems to be changing their tune, going from rather dismissive at first to having their COO, Sheryl Sandberg, apologized to the media recently.

Interestingly, Adam Kramer, one of the authors of the study, was quoted as saying that “the research benefits of the paper may not have justified all the anxiety.”

For Facebook however, the anxiety, and possible legal ramifications, might just be beginning.