Facebook to Devs: Stop Using Data for Surveillance It's now explicitly against Facebook policy to harness user data for mass surveillance, a move that privacy groups like the ACLU hailed.

Facebook's user data is the company's lifeblood, sustaining the advertising platform of the world's largest social network. But it's not just advertisers who want that data: spies and law enforcement agencies would also like to get their hands on it. Facebook on Monday made it a bit harder for them to get it.

A new update to the company's developer rules prohibits the use of Facebook data in surveillance tools, something that Facebook said was already against its policies but not explicit enough. The update explains that developers cannot "use data obtained from us to provide tools that are used for surveillance," according to a Facebook post from Deputy Chief Privacy Officer Rob Sherman.

"Our goal is to make our policy explicit," Sherman wrote. "Over the past several months we have taken enforcement action against developers who created and marketed tools meant for surveillance, in violation of our existing policies; we want to be sure everyone understands the underlying policy and how to comply."

Although Sherman did not specifically mention law enforcement use of data as a catalyst for the updated policy, he said Facebook had been working with the American Civil Liberties Union and other advocacy groups to address surveillance on social media. The groups hailed the change, explaining that it would protect users against mass police surveillance of activists and protesters.

"When technology companies allow their platforms and devices to be used to conduct mass surveillance of activists and other targeted communities, it chills democratic dissent and gives authoritarianism a license to thrive," Malkia Cyril, executive director of the Center for Media Justice, said in a statement.

An ACLU investigation last fall found that police in Baltimore and Oakland, Calif., used analytics and search tools from Geofeedia to monitor protests. Geofeedia's analytics software used data from Twitter, Facebook and Instagram, all three of which suspended Geofeedia's access shortly after the investigation.

While Facebook is making it harder for third-party developers to conduct surveillance on its users, it is nevertheless subject to the same subpoenas and other similar requests for data that come directly from law enforcement agencies themselves. Those requests have increased sharply in recent years.