The Department of Homeland Security (DHS) is likely the single largest collector and consumer in the U.S. government of detailed, often intimate, information about Americans and foreigners alike. The department stores and analyzes this information using vast data systems to determine who can enter the country and who is subjected to intrusive inspections, including by parsing through travel records, social media data, non-immigrant visa applications, and other information to detect patterns of behavior that the department has determined are worthy of scrutiny. As we explain in a new Brennan Center report, these systems ... are too often deployed in discriminatory ways that violate Americans' constitutional rights and civil liberties. It is past time for DHS to stop improvising how it designs and implements its automated systems, with inadequate mechanisms for evaluation and oversight, weak standards, and disproportionate impacts on marginalized communities and individuals. DHS must disclose additional information about its systems, including the policies that govern their operations and reports explaining how they are used. An independent body should undertake a rigorous investigation of DHS's automated systems, evaluating whether they are useful and accurate, assessing how they function, and determining whether they contain sufficient safeguards to protect privacy, civil rights, and civil liberties.