Facebook’s fight against prosecutors over nearly 400 search warrants for users’ postings and other data is drawing support from social media companies and civil libertarians.

Lawyers for Foursquare, Kickstarter, Meetup, and Tumblr said Monday they were seeking to join the clash on Facebook’s side. The New York Civil Liberties Union and the American Civil Liberties Union also recently said they were backing Facebook (NYLJ, Aug. 8).

They see the warrants—or data including friend lists, photos and private messages, many of them from users who have yet to be charged and may never be—as a troubling message for digital-age privacy. Facebook has said it had previously never received so many search warrants.

“With the burgeoning tech industry in New York, the need to protect the privacy of users has never been greater,” said Richard Holwell, of Howell Shuster and & Goldberg, a former federal judge who’s now in private practice and representing the four tech companies, all New York-based.

The Manhattan District Attorney’s Office, which sought the data for a sweeping disabilities-benefit fraud investigation, argues that the warrants were justified. Some 134 people have been charged so far, more than half have pleaded guilty, and prosecutors have said more could be implicated.

“Prosecutors have a right and a responsibility to collect evidence in criminal cases, wherever that information is stored,” Joan Vollero, spokeswoman for the district attorney’s office, said Monday.

Acting Supreme Court Justice Melissa Jackson denied a motion by Facebook to quash the warrants.

She approved the 381 warrants in July 2013, saying law enforcement has authority to search massive amounts of material to seek evidence.

She also directed Facebook not to notify the affected customers about the warrants. The case was secret until it was unsealed and Facebook disclosed it in June.

Facebook and its supporters say that the judge’s orders violated the First and Fourth Amendments to the Constitution.

The Menlo Park, California-based company has turned over the information but is appealing the court order that required it to do so to the Appellate Division, First Department. The district attorney has moved to dismiss the appeal.

The case involves police and fire retirees, allegedly instructed to claim they were too psychologically devastated to work. Instead, they led robust lives—some flew helicopters, traveled overseas, did martial arts, went fishing—and sometimes aired the alleged proof of their active lives on Facebook, prosecutors say.

Prosecutors have said they gave the judge 93 pages of details on why all the accounts were targeted.

But Facebook has said prosecutors cast too wide a net. Their campaign amounted to the online equivalent of searching “an entire neighborhood of nearly 400 homes,” the company said in a June court filing. The users ranged from high school students to grandparents, Facebook said.

Over the years, online companies have sometimes won, sometimes lost, in battling authorities’ demands for user information.

The case is In Re 381 Search Warrants Directed to Facebook, Inc., 30207-13.