In the year since President Donald Trump issued his “zero tolerance” and “extreme vetting” policies, the Department of Homeland Security, Immigration and Customs Enforcement (ICE), and other government agencies have ramped up social media surveillance of citizens, immigrants, and foreign visitors. How and when the technology is used remains largely unknown. On Thursday the American Civil Liberties Union and ACLU of Northern California sued the federal government for information on its social media surveillance activities, including those related to the extreme vetting initiative. “Social media surveillance has become a major priority for the federal government in recent years,” said Hugh Handeyside, senior staff attorney with the ACLU’s National Security Project. “The public has a right to know how the federal government monitors social media users and speech, whether agencies are retaining social media content, and whether the government is using surveillance products to label activists and people of color as threats to public safety based on their First Amendment-protected conduct.” The ACLU and ACLU of Northern California filed suit in the Northern District California after various agencies failed to respond to a May 2018 Freedom of Information Act (FOIA) request. According to the ACLU, the FBI could neither confirm nor deny the existence of records relating to the FOIA request. In addition to the FBI, the defendants are the DOJ, DHS, ICE, U.S. Customs and Border Protection, U.S. Citizenship and Immigration Services, and the State Department. As we reported in November, immigration and homeland security agencies depend upon a number of data mining companies to monitor social media, under contracts that are mostly hidden from public view. Alongside a ramp-up in covert internet surveillance, a growth in domestic monitoring by U.S. agencies after September 11 has laid the groundwork for companies like Palantir, which was seeded with CIA funds and has secured at least $1 billion in federal contracts since 2009. The company–whose chairman Peter Thiel was a Trump campaign supporter and is a member of Facebook’s board–is one of a number of ICE’s software suppliers. A 2016 Privacy Impact Assessment by DHS noted that personnel within ICE Enforcement and Removal Operations were using Palantir software “to manage immigration cases that are presented for criminal prosecution,” but also for non-criminal situations, “to query the system for information that supports its civil immigration enforcement cases.” The ACLU lawsuit would require government agencies to provide its guidelines on social media surveillance, as well as their communications with private businesses and social media platforms, and documents related to “the purchasing or building of social media monitoring tools, among other records.” “Multiple agencies are taking steps to monitor social media users and their speech, activities, and associations,” the complaint reads in its introduction. “According to publicly available information, Defendants are investing in technology and systems that enable the programmatic and sustained tracking of U.S. citizens and noncitizens alike.” Related: Apple’s inconvenient truth: It’s part of the data surveillance economy In the lawsuit, the ACLU expresses worry that social media surveillance will chill free speech, but also lead to targeting of racial and religious minorities, as well as those who dissent against official government policies. And any targeting of social media profiles of immigrants or those living in the U.S. under visas would most likely mean the surveillance of these individuals’ communications with other people not targeted for surveillance, including American citizens.