WASHINGTON - It was supposed to be a journey that would save her life, when U.S. immigration officials brought a 7-year-old girl named Ajlee from an asylum-seekers’ camp in the Mexican border city of Matamoros to an emergency room in Brownsville, Texas on Dec. 11. That same day, they also transported two women in need of urgent care: Yanet, with a possibly cancerous tumor, and Yoladiz, who is going blind from an untreated parasitic infection.

But the next day, all three were back in Mexico, living in tents in Matamoros with no access to the medical care they needed—despite agency guidelines requiring border officials to allow asylum-seekers with known medical issues to remain in the United States, according to the latest issue of Time magazine.

And attorneys and medical professionals say there are many more like them: individuals with health issues who’ve been caught up in the Trump Administration’s Migrant Protection Protocols, or MPP, which requires asylum-seekers to stay in Mexico while their cases are adjudicated in the U.S. Those with serious illnesses or disabilities should be exempt, but dozens have have been turned away at ports of entry and told to wait in Mexico because of MPP, according to seven lawyers and medical professionals who spoke to TIME. Human Rights First, a nonprofit, has documented several accounts of asylum-seekers, including pregnant women, children and adults with seizures, children with prosthetics and children with cerebral palsy, being returned to Tijuana, Mexicali, Juárez and Matamoros, which it calls a violation of the United States’ own immigration policies.

The MPP policy has faced legal challenges since it was implemented in January 2019, but in May, a federal appeals court allowed it to remain in place while a lawsuit challenging it continues. Meanwhile, the number of asylum-seekers who have waited on the Mexican side of the border for court dates has reached at least 56,000 since the end of November, according to the Transactional Records Access Clearinghouse, a data and research organization at Syracuse University.

The federal government’s rules state that members of “vulnerable” populations, including those with physical and mental health issues, are permitted to stay in the U.S. through the duration of their asylum cases once they present themselves to U.S. asylum officers. But Customs and Border Protection (CBP) officers have the final say, according to the agency’s guidelines.

The agency declined to comment on what further guidance or rules exist in determining who is considered vulnerable and therefor exempt from MPP.