Facebook is in legal trouble once more.

According to a recent report from BBC News, a class action lawsuit has been filed alleging that Facebook has consistently breached user privacy by scanning and monitoring private message data. More specifically, the suit claims that Facebook intercepts specific private messages – generally those including a link to a website – and uses them to monitor user internet activity. Supposedly, Facebook uses these private messages to learn more about its users, then sells that information to advertisers to make some extra profit on the side.

Precisely how many Facebook users have jumped on the bandwagon of the class action lawsuit has not been revealed. However, the suit is asking for either $10,000 per user in the class or $100 per day of privacy infringements – whichever ends up being greater. If the class is large enough, those numbers could mean big losses for Facebook. However, the social media network maintains that the class action claim is bogus, and has stated that it will fight the suit tooth and claw.

The lawsuit, which was filed earlier this week, claims that Facebook effectively built a profitable model for itself by establishing a so-called private messaging system. By allowing users to believe that their communications were private, the suit claims that Facebook encouraged its customers to let their guards down and share things via private message that they would not usually share publicly.

Therefore, if Facebook is indeed reading its users’ private messages, the site would actively be giving itself access to personal information that data aggregators and marketers could not collect by themselves. As a result, that personal data would be exceptionally valuable, and could represent a nice profit stream for the already very-profitable Facebook.

Of course, the class action lawsuit will need to do more than describe a potentially profitable system in order to win a major settlement. Supposedly, the case’s information came from “private research” which can prove that Facebook has been accessing users’ private interactions, mining data from those interactions, and selling that data to third parties. Precisely what form the evidence will take remains to be seen.

This won’t be Facebook’s first time in the courtroom for breach-of-privacy allegations. In 2011, the social media website was sued for creating customized advertising that used customer data without permission. That particular class action lawsuit led to a verdict this past summer that required Facebook to pay $20 million to 150 million plaintiffs. In other words, those plaintiffs each got about $15 in total.