Nineteen U.S. states and the District of Columbia, led by California, filed a lawsuit Monday seeking to stop a new policy the Trump administration announced last week, under which migrant families that crossed the U.S. border illegally would face indefinite detention.

Last year, Kirstjen Nielsen, who was then U.S. President Donald Trump’s secretary of homeland security, called the 20-day parameter a “legal loophole” that has allowed undocumented immigrants to remain in the United States illegally.

“Efforts to weaken or eliminate basic child protection standards by calling them a burden or loopholes, and eliminating their obligations for the basic care of children, is just another example of the administration’s abdication of human rights,” Michelle Brané, the director of the migrant rights and justice program at the Women’s Refugee Commission, told The New York Times.