Facebook has said it's appealing a ruling by a local court requiring them to hand over account information belonging to 381 users.
The social media company says Manhattan prosecutors issued several search warrants relating to an investigation about disabilities-benefits fraud.
It disclosed the nearly year-long legal fight after the filings were unsealed this week.
Facebook says prosecutors were intruding on users' privacy.
The Manhattan District Attorney's office and a judge say the warrants were justified.
Facebook says 62 of those users were among 134 people charged in the case.