For all the human brain’s mysteries, its development is quite well understood. Early childhood and adolescence are crucial times of unparalleled neural growth. Just as trust and stability can enhance that growth, fear and trauma can impede it. Institutionalization, in particular, can have profound and deleterious effects, triggering a range of developmental delays and psychiatric disorders from which recovery can be difficult, if not impossible.

In light of that knowledge, the Trump administration’s latest move against immigrant children is especially troubling. On Thursday , the Department of Homeland Security proposed new regulations that would allow the government to detain migrant children indefinitely. Officials are now prohibited from detaining such minors for more than 20 days by an agreement known as the Flores settlement, which has been in place since 1997. The new rules would end that settlement and would likely open the door to an expansion of detention centers across the country.

D.H.S. says that by eliminating Flores, officials will deter illegal immigration, reasoning that undocumented adults will be less likely to enter the country to begin with if they know they can’t avoid long-term detention simply by having a child in tow. Immigration activists say the proposed rule’s true aims are both simpler and more diabolical than that: “They want to strip away every last protection for detained immigrant children,” says Omar Jadwat, director of the American Civil Liberties Union’s Immigrants’ Rights Project.