E-Verify is a massive federal data system used to verify the eligibility of job applicants to work in the United States. The U.S. Department of Homeland Security (DHS), U.S. Citizenship and Immigration Services (USCIS), and the U.S. Social Security Administration (SSA) administer E-Verify. Until now, the federal government has not required private employers to use E-Verify, and only a few states have required it. However, a proposed bill in Congress, the Legal Workforce Act (HR 3711), aims to make E-Verify use mandatory nationwide despite all the very real privacy and accuracy issues associated with the data system. EFF recently joined human rights and workers rights organizations from across the United States and sent a letter to Congress pointing out the flaws of E-Verify.
— source eff.org 2017-10-22