In the proposed regulation, Barr describes the DNA sample as a "genetic fingerprint" that can uniquely identify a person, "but they do not disclose the individual's traits, disorders, or dispositions."
Legal permanent residents and those seeking to enter the country legally won't be affected by the new regulation. The rule will now be subject to a 20-day comment period.
But already, immigrant advocates have denounced the proposal, arguing that collecting genetic information from those crossing the border could have implications for family members residing in the U.S.
"It's the most intimate information that you can take from someone. It is information you can use to find their family members, to know their histories," Naureen Shah, senior advocacy and policy counsel at the American Civil Liberties Union, told NPR. "And we're going to be taking it from people against their will."
Other lawyers who work with immigrants also slammed the proposal, saying it raises alarming privacy concerns and will not deter migrants from entering the U.S.
"It's hard for me to believe that a woman who is on a journey of 1,000 miles in broken flip-flops with a 2-year-old on her hip, doing everything she can and sacrificing everything ... is going to be deterred by DNA collection," said Henry Sias, a Philadelphia-based civil rights lawyer who represents asylum-seekers.
Federal authorities say nearly 1 million migrants were taken into custody after crossing the southern border in the last fiscal year, but the number of migrants taken into custody in recent months has been steadily declining, which the Trump administration attributes to the crackdown on the border.