The Trump administration is seeking to end an immigration policy cornerstone that since the 1990s has offered protections to child migrants in federal custody, a move that will be challenged by advocates.

The U.S. is still separating some migrant children from parents while holding them after they cross the border despite broad improvements at detention centers in Texas.

The Biden administration plans to partially end the 27-year-old court supervision of how the federal government cares for child migrants, shortly after producing its own list of safeguards against mistreatment.