Texas Rep. Joaquin Castro leads two dozen House Democrats in calling on the Department of Homeland Security (DHS) and Department of Justice (DOJ( to open a federal investigation into Gov. Greg Abbott’s Operation Lone Star, an unconstitutional scheme that has detained asylum-seekers and migrants for weeks at a time, some for months, with no formal charges.

”These operations have continued to militarize Texas’ border communities and interfered with the federal immigration system, likely violating the Supremacy Clause of the Constitution,” legislators said. “Even more egregiously, these programs have directly led to a violation of state laws and constitutional due process rights.”

Last month, the Texas Tribune reported that Texas law “requires that defendants be released from jail if prosecutors delay cases by not filing charges quickly,” which is anywhere from 15 to 30 days for the trespassing charges Abbott has sought under his plan. But as legislators note to DHS Sec. Alejandro Mayorkas and Attorney General Merrick Garland, “the state has passed multiple state statute deadlines to file charges … as a result, almost 1,000 migrants to sit in prison for weeks and sometimes over a month.”

“Additionally, the governor’s efforts have led to the wrongful separation of families and the violation of state and federal laws,” legislators continue (click here for a full list of signatories). “In fact, there have been delays of filing charges, delays in appointing attorneys for migrants, and migrants unknowingly filling out documents they could not read to waive their right to counsel.” Civil rights groups that have gone to court on behalf of migrants have said many “were forced to sign pre-filled legal forms in English they could not understand and detained for extended periods of time in inhumane prison settings.” Many have not received any legal help at all.

But as we’ve previously noted, that’s just scratching the surface. That’s because The Texas Tribune also reported that a prosecutor dropped charges against 11 men who said that officers zip-tied their hands, forced them to climb 10-foot-fencing onto private property, then arrested them for trespassing. The report noted that the men had been imprisoned for nearly two months. Even when asylum-seekers have won release from the court, officials have unlawfully held them so Customs and Border Protection can detain them. “Attorneys chased a prison bus and threatened a lawsuit to find men arrested in Gov. Greg Abbott’s Operation Lone Star,” NBC News reported earlier this month.

Legislators in the letter ask DHS and DOJ to “review and investigate” Abbott’s scheme “regarding both its likely violation of the Supremacy Clause and its treatment of migrants, especially in regards to an individual’s constitutional right to due process.” Legislators also request more information on the “immigration process” for people detained under the scheme. “We also request that DHS provide migrants who enter into its custody after their release from state custody with timely and regular telephone access so that they can inform their loved ones and attorneys of their location,” they continued.

Advocates have been pushing for the administration to fight Abbott’s policy. “I’ve seen a lot in my time doing this work, but I have never seen something on this scale,” Grassroots Leadership Co-Executive Director Claudia Muñoz told Prism in September. “He has orchestrated this entire enforcement operation in Texas, and it’s been really effective. I keep telling people that if we don’t get a grip on this soon, it’s going to be really, really bad.” Meanwhile, Abbott’s spokesperson claimed to NBC News “that Texans deserve to have the rule of law enforced on the Texas border.” Truly, a bold claim to make when Ken Paxton is the state’s attorney general.