On November 30, 2016, James Busse, who was then thirty-five years old, arrived at New York’s John F. Kennedy airport on a return flight from Barbados, where he had been on vacation. Busse worked as a stockbroker for a firm in lower Manhattan. He was born in Barbados but came to the United States with his mother when he was less than a month old; when he was nine years old, she became a naturalized U.S. citizen. His mother had told Busse that he, too, had become a citizen, but he had never obtained a U.S. passport, though he’d had a green card since he was a baby. Instead, he travelled internationally with the documents of a citizen of Barbados and of a lawful permanent resident of the U.S.

At J.F.K., a Customs and Border Protection officer processed Busse’s fingerprints and asked him if he had ever been arrested. He admitted that he had. In 2001, when he was twenty years old, he had pleaded guilty to receiving stolen property. He was sentenced to thirty hours of community service. Later, when he was in his mid-twenties, he was convicted on a marijuana-possession charge and on another involving prostitution. Yet he never was sentenced to prison.

The inspection officers seemed concerned. They directed Busse to a secondary airport screening area. Following hours of interviews, as he recalled it, he was released, with instructions to collect documents about his criminal cases—the most recent of which was about nine years old. What followed over the next year was a disquieting story of immigration enforcement on full throttle, a system that can fail to detect when those it pursues are U.S. citizens and so should never be detained under immigration statutes or processed for deportation in the first place.

In July, 2017, after some back-and-forth with Customs and Border Protection, Busse returned to J.F.K. for what he thought was a routine appointment. He found himself in a room with eight to ten officers. As he recalled, someone informed him, “You’re going into the deportation process.” He was handcuffed, shackled, and transported to the immigration detention wing of the Bergen County Jail, in Hackensack, New Jersey.

Busse found the detention facility “pretty hard to deal with,” he told me later. He shared a cell with a detainee from Guyana and encountered others in the facility who had been there for as many as five years. Busse became so distraught that he decided to voluntarily deport himself to Barbados as quickly as possible. “I was losing it,” he told me. “I was going insane.” He had previously contemplated the possibility of trying to live in Barbados, where he had relatives. “Some things happen for a reason,” he said, explaining his thinking. On the other hand, “I didn’t think that me being picked up by ICE was a good reason” to leave behind a stockbroker job in New York for what would likely be permanent exile from the United States.

Two months after he was detained, Busse received his first hearing in immigration court, on Varick Street, in Manhattan. Immigration detainees arrive there early most weekday mornings, in shackles, wearing orange jumpsuits. When Busse arrived, he encountered a lawyer for the first time since his detention, thanks to a recent program enacted by the New York City Council, which pays lawyers to represent poor immigrant detainees. At “intake,” Gregory Copeland, a staff attorney at Legal Aid, appeared before a group of between ten and twenty detainees, and he and a colleague made a short presentation in English and Spanish. When Busse’s turn for a private consultation arrived, he declared that he wanted to accept deportation to Barbados. He was “very angry—extremely angry” about what had happened to him, Copeland told me.

As they talked, however, Copeland realized that, under the law, Busse was almost certainly a United States citizen. In the labyrinth that is U.S. immigration law, certain immigrants automatically become citizens if, when they are minors, their parents become naturalized citizens. Busse met the requirements because, in addition to his mother’s naturalization, his father, who was Canadian, had died when he was thirteen.

Copeland advised Busse that he had a very promising claim that would allow him to leave the Bergen County detention facility and avoid deportation altogether. Yet Busse replied emphatically that he could not take being jailed much longer. One way or another, he wanted his situation resolved within weeks.

Gregory Copeland’s mother is a genealogy enthusiast; that night, the lawyer enlisted her to search through Web sites that post searchable photos of tombstones in order to help researchers trace their family histories. Among other pieces of evidence, Copeland’s mother found online a photo of a tombstone in Quebec bearing the name of Busse’s father, Henri Joseph Gerard Busse. In the end, an immigration judge dismissed his deportation case. (Busse is now seeking documented recognition as a U.S. citizen.)

The fact that Busse was almost deported from a country where he should have been protected by law as a citizen should not be understood as a freak mistake. For decades, U.S. citizens have been deported repeatedly, in isolated cases and en masse, due to racism and bureaucratic indifference, as well as the complexity of federal immigration laws, which can make it difficult for some bona-fide U.S. citizens to understand and document their status. The federal government possesses no definitive list of U.S. citizens that could be checked in a case like Busse’s. The closest thing to such a list, the federal database of Social Security numbers, encompasses a workforce combining both citizens and legally authorized noncitizens.

From the nineteen-thirties through the fifties, the deportation of non-Anglo U.S. citizens was carried out in purposeful and large-scale campaigns, often driven by racism. During the Depression, between 1929 and 1937, U.S. authorities rounded up about four hundred and fifty thousand Mexican-Americans. According to one report, cited in “Operation Wetback,” a study by the historian Jerry Cunningham, as many as half of these were legally U.S. citizens. The deportees were shipped in buses and boxcars to Mexico. Two decades later, during the militarized sweeps and deportations of Operation Wetback, ordered by President Dwight D. Eisenhower amid the anti-Communist hysteria of 1954 and 1955, many other citizens were packed off to Mexico.

Even today, a case like Busse’s cannot be dismissed as an aberration. Davino Watson, a U.S. citizen born in Jamaica, was held in an Immigration and Customs Enforcement detention facility for three years, despite informing ICE that he was a citizen. (His repeated statements that he was a citizen and his appeals of his case eventually prompted ICE to look at his case more thoroughly, after which it released him.) Immigration attorneys I spoke with said they and public defenders assigned to noncitizens in criminal matters regularly encountered cases raising the same issues as those of Busse and Watson. Copeland said he is working on five others currently. NPR has reported that its analysis of data obtained through the Freedom of Information Act showed that in the decade between 2007 and July of last year, six hundred and ninety-three U.S. citizens were held in county jails under immigration detention orders. A separate request by the Northwestern University professor Jacqueline Stevens found that another eight hundred and eighteen were held in immigration detention centers. That’s a rough average of a hundred and fifty mistaken detentions of Americans every year.

Department of Homeland Security regulations require ICE and other immigration officers to investigate any detainee’s claim of citizenship or to probe independently when the evidence suggests a detainee might be an American. The Justice Department, which houses the country’s immigration courts, funds a program to promote detainees’ access to pro-bono counsel and to information about their rights, but it stops short of funding individual representation for those who cannot afford it. Clearly, that program and the D.H.S. regulations do not work well enough to keep all citizens out of jeopardy.