On March 29th, in Pontiac, Michigan, Sergio Perez appeared in a county courtroom to seek sole custody of his son and two daughters, who were between eleven and seventeen years old. The children lived with Sergio’s estranged wife, Rose, and, he told me recently, he was concerned about them. His wife had taken out a yearlong protective order against her boyfriend in 2015, but, as far as Sergio knew, they now lived together. (Rose and the boyfriend could not be reached.) Perez paid the rent on the house where his children and Rose lived, he told me, although he had fallen thousands of dollars behind on child support. (He said that he spent other money on the children directly—for example, for their clothes.) Perez ran a small contracting business near Pontiac, installing carpets. He said that he wanted “to see my daughters do well, with modern lives.” He was “never rich at all,” but he was “working fourteen, sixteen hours a day,” he told me. “I was working three customers a day.”

Rose and the three children are all United States citizens, but Perez was undocumented. He had grown up in Guadalajara, Mexico, and crossed into the United States, without authorization, when he was nineteen. During the next twenty-one years, he and his attorney, Bethany McAllister, told me, he had moved back and forth to Mexico, and he had been deported several times before. But otherwise he had never been arrested or convicted of a crime, and had received only one ticket, for driving on an expired license. Amid the anti-immigrant fever created by the Trump Administration, he feared that pressing the custody case might lead to someone informing on him to Immigration and Customs Enforcement, or ICE, in order to have him arrested and deported to Mexico. Perez decided to go to family court anyway. He said that he wanted to show his children that “no matter how hard or difficult it might be, you have to do what you have to do, no matter what.”

In the courtroom on March 29th, he heard his name called out, and entered a side room. There were men in plain clothes; one identified himself as Anthony. “I’ve been looking for you,” he said, as Perez recalled. The man pulled out a badge. “We’re with ICE.” (The arresting agents were from Border Patrol, and they transferred Perez to ICE custody.*) The agents arrested Perez right there, transported him to a jail in Dearborn, and then later transferred him to a detention center in Louisiana. McAllister, Perez’s attorney, urged the ICE field office in Michigan to reëxamine his case and to stay his deportation, in the interests of his children. Two attorneys from the Michigan chapter of the American Civil Liberties Union, Michael Steinberg and Juan Caballero, also wrote to ICE, noting, “This practice of obstructing non-citizens’ access to courts endangers public safety and has a chilling effect on families seeking protections from the court.” Their efforts didn’t work. ICE deported Perez to Mexico City.

When I caught up with Perez recently by telephone, he was back in Guadalajara, where he was working as a waiter and a translator. He remained worried about his children, he said. He had promised McAllister that he would not cross the U.S. border again without authorization, so he was trying to find some legal way forward. “I want to go back and change my daughters’ lives,” and also his son’s, he said.

One of the most disturbing aspects of “interior enforcement” of the immigration laws—meaning arrests and detentions carried out far from the American border, typically by ICE agents—is that the actions can pollute the administration of justice and undermine the rights that the Constitution affords all criminal defendants, whether they are U.S. citizens or not. Because immigration-removal proceedings are generally carried out under civil laws, they are exempt from many procedures mandated in criminal cases. For example, the warrants that ICE uses to arrest unauthorized immigrants like Perez aren’t reviewed by a judge; they’re just written up by ICE office supervisors. Immigrant detainees don’t have a constitutional right to a lawyer. Fourth Amendment protections against unreasonable search and seizure don’t always apply when ICE agents investigate a target for arrest, because the cases typically don’t involve a criminal prosecution. This troubling and confusing inheritance of immigration policing has now been made worse by the Trump Administration’s expansion of arrest operations in American courthouses.

The Immigrant Defense Project, an advocacy group based in New York City, said that it had received reports of eighty-four arrests and attempted arrests in courthouses in New York this year through September, more than six hundred per cent more reports than it had received last year, including fifty-one arrests in or around New York City courthouses. Most often, ICE agents target criminal defendants who may be deportable, but they have also arrested people in New York family court, juvenile court, and specialized courts devoted to the prevention of human trafficking.

According to an Immigrant Defense investigation, in April, in Suffolk County Family Court, ICE arrested a Pakistani-born father who had appeared on “a visitation matter.” The father was the primary custodian of two children who were United States citizens. He himself had come to the United States as a five-year-old child, “when his family fled political persecution in Pakistan.” In June, in Queens, ICE officers followed a woman who had appeared in Human Trafficking Intervention Court. The agents arrested the woman as she walked to the subway. On September 27th, ICE agents arrested a victim of alleged domestic violence as he left Queens County Criminal Court.

Wendy Wayne, who directs the Immigration Impact Unit at the Massachusetts public defender’s office, told me that the surge of courthouse immigration arrests across the country, including in Massachusetts, “has a tremendously negative impact,” because “defendants are being arrested before they resolve their criminal cases and witnesses and victims are not coming to court.” During the first six months of this year, Latinos in Los Angeles, San Diego, and San Francisco reported fewer cases of domestic violence than during the same period the year before. Advocates believe that the decline reflects less a drop in the crime rate than a rising fear among undocumented victims and witnesses that, if they seek justice, they will be deported.

Some courthouse administrators, judges, and even prosecutors, such as the acting Brooklyn District Attorney, Eric Gonzales, have tried to persuade ICE to back off. Earlier this year, Tani G. Cantil-Sakauye, the California Chief Justice, wrote in a letter to Attorney General Jeff Sessions and the former Homeland Security Secretary John Kelly, now the White House chief of staff, that “courthouses serve as a vital forum for ensuring access to justice and protecting public safety.” She accused ICE of “stalking courthouses.” Sessions and Kelly wrote in reply that, because sanctuary policies enacted by cities and jurisdictions in states such as California “prohibit or hinder” ICE from enforcing immigration laws, they had no choice but to carry out operations in courts. They reaffirmed their policy.

During the Obama Administration, ICE, through policies derived from executive orders, prevented agents from performing operations in “sensitive locations,” including houses of worship, schools, and hospitals, except in extraordinary circumstances. The Trump Administration has continued that policy, to date. Courthouses weren’t on the “sensitive locations” list, but arrests were very rare. That is what changed under Trump, Sessions, and Kelly.

Khaalid H. Walls, an ICE spokesperson, acknowledged in a statement to me that the agency continues to make arrests at courthouses, but that these generally take place “only after investigating officers have exhausted other options.” He said that many of the targeted people “have prior criminal convictions, pending charges,” and/or pose “threats to public safety.” He added that “every effort is made to take the person into custody in a secure area, out of public view, but that is not always possible.” (Last August, the American Bar Association passed a resolution urging Congress to pass a law expanding the “sensitive location” policy to include courts. There are bills pending, but their chances are doubtful.)