Intern Reema Moussa contributed to this blog post.

As government agencies increasingly use digital tools to track citizens and immigrants, we need to use the Freedom of Information Act (FOIA) to make that surveillance transparent. But while the government opens its databases to public scrutiny, it must also protect individual privacy.

Late last month, the Second Circuit Court of Appeals held that U.S. Immigration and Customs Enforcement (ICE) must be transparent and respect privacy by producing deidentified data on how it arrests, classifies, detains, and deports immigrants. The court agreed with plaintiff American Civil Liberties Union (ACLU) that ICE must also replace Alien Identification Numbers (A-Numbers), exempt from FOIA because they would identify individual immigrants, with unique but random identifiers.

This allows the public to “track datapoints pertaining to individual, unidentified aliens,” according to the court. It held that since ICE can use an A-number to get all enforcement records from its databases on an immigrant, so should the public, while respecting that individual’s privacy. The Court found this substitution of unique identifiers “does not alter the content of any record” (not required by FOIA), “but only preserves the computer function necessary to afford the public access” (required by FOIA). The court cited many examples from EFF’s amicus brief of other courts ordering the government to use such “anonymization techniques,” including unique identifiers, blurring faces in videos, and scrambling identifying data.  

The Second Circuit also cited and agreed with EFF’s amicus brief that the E-FOIA Amendments required ICE to substitute unique identifiers because that is the “form or format” ACLU requested and it is “readily reproducible.” ACLU even provided the simple lines of code that ICE could run to substitute out the exempt A-numbers. The court explained that Congress “expected agencies to take reasonable steps to effect retrieval in the requested form or format, even if that required some conversion of data.”

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