This year, states began using an expanded Department of Homeland Security system to check their voter rolls for noncitizens. The initial results, however, didn’t back up President Donald Trump’s claim that noncitizen voting is widespread. ProPublica reporter Jen Fifield spoke with experts who say the data-sharing agreement, which gives DHS access to hundreds of millions of Americans’ Social Security data, contains alarmingly few provisions to ensure accuracy, security or privacy.

Officials at U.S. Citizenship and Immigration Services, the branch of DHS that oversees the system, declined to answer questions from ProPublica.