The federal government is trying to use Medicaid data to identify and deport immigrants. So EFF and our friends at EPIC and the Protect Democracy Project have filed an amicus brief asking a judge to block this dangerous violation of federal data privacy laws.

Last month, the AP reported that the U.S. Department of Health and Human Services (HHS) had disclosed to the U.S. Department of Homeland Security (DHS) a vast trove of sensitive data obtained from states about people who obtain government-assisted health care. Medicaid is a federal program that funds health insurance for low-income people; it is partially funded and primarily managed by states. Some states, using their own funds, allow enrollment by non-citizens. HHS reportedly disclosed to DHS the Medicaid enrollee data from several of these states, including enrollee names, addresses, immigration status, and claims for health coverage.

In response, California and 19 other states sued HHS and DHS. The states allege, among other things, that these federal agencies violated (1) the data disclosure limits in the Social Security Act, the Privacy Act, and HIPAA, and (2) the notice-and-comment requirements for rulemaking under the Administrative Procedure Act (APA).

Our amicus brief argues that (1) disclosure of sensitive Medicaid data causes a severe privacy harm to the enrolled individuals, (2) the APA empowers federal courts to block unlawful disclosure of personal data between federal agencies, and (3) the broader public is harmed by these agencies’ lack of transparency about these radical changes in data governance.

A new agency agreement, recently reported by the AP, allows Immigration and Customs Enforcement (ICE) to access the personal data of Medicaid enrollees held by HHS’ Centers for Medicare and Medicaid Services (CMS). The agreement states: “ICE will use the CMS data to allow ICE to receive identity and location information on aliens identified by ICE.”

In the 1970s, in the wake of the Watergate and COINTELPRO scandals, Congress wisely enacted numerous laws to protect our data privacy from government misuse. This includes strict legal limits on disclosure of personal data within an agency, or from one agency to another. EFF sued over DOGE agents grabbing personal data from the U.S. Office of Personnel Management, and filed an amicus brief in a suit challenging ICE grabbing taxpayer data. We’ve also reported on the U.S. Department of Agriculture’s grab of food stamp data and DHS’s potential grab of postal data. And we’ve written about the dangers of consolidating all government information.

We have data protection rules for good reason, and these latest data grabs are exactly why.

You can read our new amicus brief here.