After lawyers intervened on the girl’s behalf, arguing that her rights had been violated during the expulsion, she was allowed into the United States and is now living in a shelter in Arizona. Her father said he is waiting for permission from the U.S. government to be reunited with his daughter.

“I’ve been out of my mind,” he said. “This is a really, really stressful situation. It’s about your kids, you want always the best for them, but at the same time you know that you can’t physically protect them or do anything right now, so that is really frustrating.”

Lawyers for the American Civil Liberties Union are challenging the practice of expelling migrant children in federal court, arguing that it violates child welfare laws, such as the Trafficking Victims Protection Act, as well as national immigration laws, which require special protections for migrant children traveling alone.

“Even apart from the general illegality of Title 42, it is separately illegal under the immigration laws to expel a non-Mexican child to Mexico,” said Lee Gelernt, the lead attorney in the case.

The government has recently begun referring to migrant children who cross the border alone differently — as “single minors” rather than “unaccompanied alien children” — reinforcing the notion that while the pandemic-related border closure is in place, such children are not eligible for the legal protections that would otherwise have been available to them.

According to public data, U.S. authorities have expelled more than 200,000 people since the new public health border closure took effect, but the administration would not answer questions about how many of them were children, nor about how many were sent to Mexico. In December, border authorities acknowledged in federal court that at least 8,800 children have been expelled from the United States since March.

The human rights organization Women’s Refugee Commission, working with several other advocacy organizations, filed a public records request with Mexican authorities and received data suggesting that at least 208 Central American children had been returned to the custody of Mexican authorities between March 21 and June 5 of this year.