Southern District Judge Shira A. Scheindlin has ordered the release of a document expected to show why a U.S. program for identifying deportable immigrants after they have been detained was made mandatory. The judge has ordered the government to turn over a key memorandum by Nov. 1 to civil rights groups and immigrant advocates.

In a statement, the plaintiffs assert that the judge’s order will shine light on a program plagued with secrecy and lies. The document had been withheld from a Freedom of Information Act request. The Secure Communities program enables the fingerprints of detainees arrested locally to be shared with federal authorities. Critics say the program has made immigrants reluctant to report crime because they fear deportation. A government spokeswoman did not immediately return a call for comment.