A lawsuit was filed earlier this week, claiming that Facebook scans messages between users marked as "private" and sells the information to outside sources.
The suit was filed by Matthew Campbell and Michael Hurley in a U.S. district court in Northern California, according to CNN Money.
They want the suit to be made a class action, suggesting that as many as 166 million Facebook users in the U.S. would be eligible to join.
Campbell and Hurley say the viewing of private messages was done without knowledge of the Facebook users.
"Facebook's desire to harness the myriad data points of its users has led to overreach and intrusion ... as it mines its account holders' private communications for monetary gain," the plaintiffs allege.
Facebook said in a statement that they believe the allegations are "without merit."