“Following EFF’s victory in a four-year Freedom of Information Act lawsuit, the government released an opinion, written by the Office of Legal Counsel (OLC) in 2010, that concluded that Section 215—the provision of the Patriot Act the NSA relies on to collect millions of Americans’ phone records—does have a limit: census date The Commerce Department requested an OLC opinion on whether any provisions of the Patriot Act could override the privacy requirements of the Census Act, provisions which, as the opinion acknowledges, “have long provided assurances of confidentiality to” census participants. The opinion contrasts the “broad authority” and “substantial new powers” provided by Section 215 with the “long history of congressional enactments providing broad confidentiality protection to census information.” Ultimately, OLC concluded that “section 215 should not be construed to repeal otherwise applicable Census Act protections for covered census information” and that the “Patriot Act, as amended, does not alter the confidentiality” of census data. That, however, was not the view of Department of Justice’s National Security Division (NSD). As the opinion notes, the National Security Division “disagreed, contending that section 215 . . . may allow for a court order to compel the Secretary [of Commerce] to disclose furnished census information.” Importantly, the National Security Division is the division of DOJ that represents the government in cases before the Foreign Intelligence Surveillance Court (FISC), the secret court that oversees much of the government’s domestic spying operations. Thanks to disclosures in EFF’s lawsuit, we know that NSD ultimately cited and relied on this opinion in proceedings before the FISC. That application, however, remains secret.”